166 Herbert L. Hawkins — Studies on the Echinoidea, etc. 



a typical specimen of his C. semisulcatus, sent a specimen from the 

 Inferior Oolite of Whitwell. The actual holotype was lost hy this 

 time, so that this specimen came to be regarded as the true repre- 

 sentative of the species, in defiance of the references of 1829. 



The year 1856 was a critical one in the history of the specific 

 name. Both Wright and Salter then came to recognize the essential 

 difference between the lower and middle Oolitic species, and, owing 

 to Phillips' error, applied the name semisulcatus to the Inferior Oolite 

 form. The degree of confidence, coupled with lack of logic, with 

 which this wrong determination was made, can be gauged by the 

 following quotation from "Wright (Pal. Soc, Ool. Ech.) : " It was 

 an error in the determination of the species, which led Professor 

 Phillips to state that Pygaster semisulcatus was found in the Coralline 

 Oolite of Yorkshire, that form never yet having been found in 

 Yorkshire out of the Whitwell beds — Inf. or Great Oolite." It is 

 difficult to understand how an author could be in error in the 

 determination of a new species at the time when he first recorded and 

 figured it, especially since the other form with which he is supposed 

 to have confused it had not been recognized at the time ; but it was 

 from this paradoxical conclusion of Wright that issued all the 

 confusion in the misapplication of the name. Save for a passing 

 reference by Desor (Synopsis), the name Pygaster semisulcatus has 

 not been applied to a Corallian species since 1856 ! 



Apart from the fact that the original reference to Clypeus semi- 

 sulcatus included solely Corallian localities, the figure given, though 

 imperfect in some respects, shows quite clearly the pyriform shape of 

 the periproct — a feature utterly unlike anything found in any 

 Inferior Oolite species. The climax of the unnecessary confusion 

 introduced in 1851 is found in the third edition of Phillips' work (by 

 Etheridge) in 1875. Here the original figure of 1829 is reprinted, 

 and referred to as Pygaster umbrella, Agassiz, while the name 

 semisulcatus is transferred to the Whitwell forms on the same page. 

 Such a glaring absurdity cannot be allowed to remain. 



As stated above, the type of Clypeus semisulcatus was lost before 

 1856, and has not been seen since. Even if it is still in existence 

 (or if any one specimen was actually selected in 1829), it would be 

 impossible to identify it with certainty. No description or measure- 

 ment was given, nor could the latter be deduced from the drawing. 

 This is said to be two-thirds of the natural size, but, since the 

 specimen is viewed obliquely, neither diameter nor height could be 

 accurately calculated. It becomes necessary, therefore, to select 

 a specimen to replace the missing holotype, so that future references 

 may rest on a more secure foundation than Hitherto. Malton was 

 the first mentioned locality, and from the quarries near that town 

 specimens are still obtainable. A very beautiful specimen from this 

 locality is in the British Museum (No. E 1645). It is the one used 

 by Wright for his drawings of the adoral surface and apical system 

 of u P. umbrella" (Pal. Soc, Ool. Ech., pi. xx, figs, lb, e) y and 

 I hereby select it as the lectotype (also a topotype) of Pygaster semi- 

 sulcatus, Phill., sp. This specimen thereby becomes the type of the 

 genus Pygaster, Agass. 



