Morphological Studies on the Echinoidea Holectypoida and their Allies

Abstract

AMONG the Echinoids from the Limestone Lenticles of Shenley Hill (Leighton Buzzard), sent to me from the Sedgwick Museum, Cambridge (see Geol. Mag., Vol. LVIII, 1921, p. 57), one specimen of the many Pyriniform examples at once attracted attention by its preservation, relatively large size, and superficial resemblance to Holectypus. A brief comment on the specimen (No. 3 of the series) was made in the note already cited; further and more detailed examination, preceded by removal of matrix, has revealed additional features of much interest. Though averse to diagnosis of new genera or species based on single specimens, I have felt compelled to adopt that course in this case, in default of acquaintance with any described types to which the Shenley Echinoid could be assimilated. It is quite likely that other specimens, congeneric if not conspecific, may exist in collections; according to their preservation or the idiosyncrasy of individuals they may be labelled Holectypus, Conulus, or Pyrina with equal probability. It is even possible that some of the numerous species of Pyrina (including Pseudopyrina and Globator), already described, may be referable to the genus here introduced; but more details of morphology than are often supplied in systematic diagnoses and figures are needed before order can come out of the chaotic series of Cretaceous Echinonëidæ.