IV.—On some Cretaceous Shells from Egypt

Extract

A Collection of Invertebrate fossils, obtained from various horizons and localities in Egypt and consisting principally of molluscan remains, has been sent home for examination and description by Captain H. G. Lyons, R.E., Director of the Geological Survey of that country.

The oldest specimens represented belong to Upper Cretaceous rocks, and are dealt with in the present communication. They include one species of Gasteropod and eight Lamellibranchs, two of the latter group being regarded as hitherto undescribed forms. It need hardly be stated here that most of our knowledge respecting these groups of Mollusca as represented in Egypt during this period has been ably summarized by Professor Dr. von Zittel, in his elaborate memoir, “Beiträge zur Geologie und Palaeontologie der Libyschen Wiiste und der angrenzenden Gebiete von Aegypten,” published in the Paleaontographica for 1883. For subsequent details we are mainly indebted to the researches of Professor Mayer-Eymar and Prof. Johannes Walther: to the former for his monograph, “Zur Geologie Egyptens,” which includes a list of Cretaceous shells from the neighbourhood of the Great Pyramid; and to the latter for his paper, “L'Apparition de la Craie aux Environs des Pyramides,” containing a list of molluscan species from the same distinct and horizon, though particularly localized as Abu Eoasch, Golea, etc.

A paucity of Gasteropod species is noticeable in the faunistic lists of the Upper Cretaceous period of Egypt, with, however, a large representation of bivalve mollusca. The most abundant forms appear to belong to the genus Ostrea and its allies, a fact also observable in the corresponding faunas of Algeria and Tunis. In all three countries a similar conchological facies is apparent, whilst some species show a marked resemblance to Syrian forms. Certain difficulties have arisen in assigning a satisfactory horizon to the Egyptian species here discussed, though the evidence appears to be in favour of a Turonian age—an opinion somewhat suggested by the palaaontological work of M. Jules Welsch, who has discovered in Algeria, Sphærulites (Sauvagesia) Sharpei, Bayle, a typical Turoniiin shell of Portugal, associated with Ostrea acanihonota, O. Boncheroni, etc. This author, therefore, inclines to the belief that the majority of Algerian species hitherto recognised by Coquand, Peron, and others as of Santonian age, are more probably Turonian. If this be accepted, then the Cretaceous rocks near Cairo (Abu Roasch, etc.), containing similar shells, which have been considered as Senonian by Schweinfurth, Walther, etc., should equally be regarded as Turonian, though apparently the Portuguese mollusc, Sauvagesia Sharpei, has not yet been identified in Egypt.