The results of Mr. W. S. Valiant's long search for the appendages of Trilobites have recently been made known by Mr. W. B. Matthew, who described the material sold to the Columbia College of New York by Mr. Valiant. Mr. Valiant informs me that he discovered traces of what he considered to be antennæ, and that for several years he continued collecting until he found a locality where the specimens were well preserved and showed, not only the antennæ, but legs and what he supposed to be the swimming appendages.

The genotype of Bryograptus, B. kjerulfi Lapworth, is figured and redescribed together with B. ramosus Brøgger, B. bröggeri Monsen and Pseudobryograptus cumbrensis (Elles).

WHILE Michell's interest in geology lasted until at least 1788, he made no further known contribution to the study of earthquakes. He must have been aware of the disastrous Calabrian earthquakes of 1783, but he would no doubt regard them as timely illustrations of his theory. The eighty years which followed 1760 were, indeed, somewhat barren as regards the progress of seismology. Among the more important contributions during this period were Dolomieu's report on the Calabrian earthquakes of 1783, Darwin's memoir on the connexion of certain volcanic phenomena in South America (1838), and the well-known chapters in Lyell's Principles of Geology (1830).

At the present time we are only fully acquainted with the geology and palæontology of one division of the great Carboniferous Series developed in Devon and the adjacent counties, the Lower Culm Measures. This division, while representing only a small fraction of thickness of the Culm Measures as a whole, is of special interest both lithologically and palæontologically, as was shown by Messrs. Hinde & Fox in an admirable paper published in 1895. Above the limestones and cherts of the Lower Culm Measures lie the great thickness of sandstones and shales which constitute the Upper of the twofold primary division of these rocks instituted by Sedgwick & Murchison in 1840. The Upper Culm Measures occupy an area of more than 1,000 square miles, and are of Upper Carboniferous age.

With the exception of the researches of the late Townshend Hall, and more recently of Mr. Ussher, comparatively little has been added to our knowledge of these beds since the days of Sedgwick & Murchison, and of De la Beche. An inquiry with regard to the palæontology, and more especially the palæobotany, of these rocks has, however, been in progress for some time past, with the result that sufficient material has been gathered for a contribution to the fossil flora of the Upper Carboniferous rocks of Devon, which, it is hoped will be published shortly by one of us. While examining the sandstones and shales of this series, other discoveries have been made, incidental to the work of collection of plant-remains.

The coarse porphyritic Aswan Granite used in many ancient Egyptian monuments has been held to intrude a tract of gneisses and schists. It is suggested in this paper that the granitic body was formed during a phase of granitization which followed the folding and metamorphism responsible for producing the gneisses and schists. A part of the granite retains mimetic structures inherited from the pre-existing rocks, but the southern part became mobile and developed a new structure. The intrusion of a magmatic granite in dykes and sheets followed the phase of granitization.

Banding, recorded by previous workers in hornblende picrite and dolerite intrusions near Rhiw, is found to be rhythmic layering. At least three major units (200 to 250 feet in thickness) have been recognized, and intermediate and minor scale units also occur, predominantly within the basal major unit. The majority of the rocks display cumulate textures, and crystallization appears to have been completed by heteradcumulus or adcumulus growth. Thin coarser-grained sheets, rich in plagioclase, and slightly discordant to the layering, are considered to be contemporaneous segregation veins.

In two previous papers in this Magazine (Hawkins, 1910 and 1911) I have dealt with some features in the comparative anatomy of the ambulacral and interambulacral areas of the Holectypoida. The only other structure of the test for a comparative study of which sufficient material is available is the apical system. The present paper deals with this structure. I intend to summarize the results of my researches in a scheme for the classification and evolution of the group in a paper already partly prepared.

I am indebted to Mr. Alfred Brown, of Aliwal North, for the opportunity of describing a small fragment of a lower jaw of a Labyrinthodont which shows some unusual characters in the dentition and in the composition of the mandible (Pl. XIX, Fig. 1). Hitherto the evidence of the structure of the mandible has been imperfectly recorded in these South African reptiles.

Mr. Brown's specimen is a small transverse segment, probably from the left ramus, at some little distance behind the symphysis. This position may be indicated by an angular ridge upon the inner side, which is becoming more elevated as it extends forward. There is no suggestion of the original length of the mandible, which may have been eighteen inches. The fragment is little more than an inch and a half long. In section the jaw is subquadrate, somewhat depressed, being two inches wide and an inch and a half deep. The external surface of the bones shows no trace of sculpture. From its slightly water-worn condition the specimen (Fig. 1) was probably obtained from the reconstructed bed at the railway station at Aliwal North, which yields Theriodonts and other fossils.

The external bone is apparently vertical, traversed on the lower third by a deep longitudinal groove, in which there is a faintly marked suture. The dentary bone above the groove is slightly convex up to the alveolar margin, and shows what may be a sinuous impression above the groove. The bone below the groove, which may be infra-dentary, is well rounded on to the base.

The most important geological problem, and the one of all others which at present excites the greatest attention, is the cause of those extraordinary changes of climate which have taken place during past ages. How are we to account for the cold and Arctic condition of things which prevailed in temperate regions during what is called the Glacial Epoch, or for the warm and temperate climate enjoyed by the Arctic regions, probably up to the Pole, during part of the Miocene and other periods? Theories of the cause of those changes, of the most diverse and opposite character, have been keenly advocated, and one important result of the discussions which have recently taken place is the narrowing of the field of inquiry and the bringing of the question within proper limits.

In the “Catalogue of Fossil Fishes in the British Museum“ (pt. i. 1889, p. 76, pl. iii. fig. 1), the imperfect rostrum of a Selachian fish from the Upper Cretaceous of Mount Lebanon was described under the new generic and specific name of Sclerorhynchm atavus. Presenting some resemblances to the rostrum both of the typical saw-fish (Prislis) and of PristiopJtorus, hesitation was expressed in determining the systematic position of the genus to which the fossil pertained; but from the apparently complex nature of the rostral cartilages and the absence of extended prepalatines, it was deemed advisable to place the fish provisionally in the family of Pristidæ.

In every correlation exercise the diachroneity of the lithostratigraphic boundaries determines the discrepancy between lithostratigraphic correlation and time-correlation. Here it is shown that diachroneity varies in degree as a simple function of the direction in which correlation is made, and hence that stratigraphic correlation must take that direction into account. When the direction of correlation is not known, a sound strategy for time-correlation of lithostratigraphic boundaries is to assume that each is at its most diachronous.

Whatever may be the precise biological value of this genus or subgenus as distinct from Purpura, it forms a remarkable group, limited, according to our present knowledge, both in time and space. Of the conditions favourable to its development we only obtain glimpses here and there. In the Coral Rag of Yorkshire one would say that the genus displays a remarkable tendency to variability within certain limits, so much so that almost every specimen found in anything like a decent state of preservation differs in some point of ornament: hence the extreme difficulty of specific arrangement. One might almost suppose that, like the Ammonite, the genus having worked out the limits of possible change, flourished within a short period only, and speedily became extinct.

In these notes it is my object to describe and figure some of the more imporant Chalk Polyzoa that have not yet been described, or have been described from material less complete than mine.

The occurrence of two Archæan groups in Shropshire is now well known to geologists. The chain of hills which strikes to the south-west from Lilleshall, north-east of Wellington, to the region south of Church-Stretton, is mainly composed of bedded volcanic rocks; but gneissic and granitoid types have been recognized at the Ercal and at Primrose Hill, the elevations forming the opposite extremities of the Wrekin, and a small exposure was detected near Hope Bowdler, east of Church-Stretton. A second axis of the old rocks, ranging parallel to the Wrekin chain, consists of volcanic ejecta and highly indurated grits, which are probably to be referred to the younger of the two Archæan groups hitherto recognized in the county. The relations between the volcanic and the gneissic systems is clearly defined by the Charlton Hill (see map) conglomerate (a band in the volcanic series), which contains numerous well-rounded pebbles of rock precisely similar to the granitoid gneiss of Primrose Hill. This fact implies a considerable break between the two groups.

The Cheviot district is largely composed of those quartzless porphyritic rocks to which the term porphyrite has been applied both by English and Continental petrologists. The Cheviot porphyrites are characterized by a compact felsitic ground-mass, throughout which are scattered numerous crystals of felspar, mostly belonging to triclinic species. The ground-mass varies in colour; the two principal shades being dark purple and red. These porphyrites are evidently more or less altered rocks and sometimes the alteration has been carried so far as to make it almost, if not quite impossible to recognize their original nature by macroscopic examination. Amygdaloidal varieties are not uncommon, and in these agates are frequently found. In addition to the ordinary porphyrites, there occur masses of volcanic ash and breccia, and also a remarkable rock which has been called pitchstone-porphyrite. This is dark almost black in colour, with a well-marked resinous lustre and a specific gravity lying between 2·53 and 2·62. It is porphyritic in texture; the large crystals consisting of a fresh glassy-looking triclinic felspar. Red veins usually traverse the rock in different directions. The boulders lying in the streams are covered with a thin light-coloured crust due to weathering, but at a distance of a quarter of an inch from the surface, or even less, the fresh unaltered rock is always found.

The Iranian territory is composed of a mosaic of tectonic units, several of which underwent in the Permian and Triassic periods a migration from northern Gondwana to southern Laurussia associated with the opening of the Neo-Tethys Ocean. Although this broad outline of Permo-Triassic palaeogeographical evolution of Iranian microplates is now widely accepted, the individual timing of migration of these blocks, and their biogeographical relationships, remain insufficiently known. Here I review the Late Palaeozoic record of trilobites in Iran and Armenia, and discuss their palaeobiogeographical affinities in an attempt to shed light on the Permian palaeogeographical evolution of Iranian and Armenian terranes. Seven Iranian or Armenian localities, representative of five tectonic units, have yielded Carboniferous and Permian trilobites. Ten species are recognized, including two new taxa, Persia praecox gen. nov. sp. nov. and Pseudophillipsia (s.l.) parvizii sp. nov. P. praecox is the only Carboniferous (Tournaisian) species. The others are Wordian to Wuchiapingian in age and can be separated into three morphological groups, probably representing clades. One is composed of representatives of Acropyge, while the two others (armenica-group and paffenholzi-group) comprise species of Pseudophillipsia. Only P. (s.l.) parvizii sp. nov. from the Zagros Mountains (Arabian Plate) is not attributed to one of these groups. The distribution of trilobites in Iran and Armenia strongly suggests that the Alborz, Central Iran and Transcaucasia microplates represented a single biogeographical unit in Middle and Late Permian times. Special relationships of this biochore with South China can also be stressed.

The collections described by Mr. Spath were made during Sir Martin Conway's Expedition across Spitsbergen in 1896, and include also those then collected by Professor Garwood and presented by him to the British Museum of Natural History.