Published online by Cambridge University Press: 11 May 2009
As certain previous authors have observed, T. larynx is a species subject to much variation. Disregard of this has led to the erection of invalid species.
The descriptive characters used by Allman are discussed. In a comparison with material collected in Plymouth Sound these characters are shown to be so variable that used singly they are valueless. In particular, disregard of the stage of development and over-emphasis on size will be very misleading.
The causes of some of this variability are suggested.