398 Dr. P. H. Carpenter on the 



a Pal^ocrinoicl, like the calyx-plates of the dorsal side, with 

 which they were universally regarded as homologous, were 

 placed on the extreme outside of the body, nothing but a thin 

 film of perisome, covered by a pavement epithelium, interven- 

 ing between the plates and the surrounding water. But we 

 are now told as a positive fact, on the authority of Messrs. 

 Wachsmuth and Springer, than which there is none higher, 

 that Crotalocrinus and the Ichthyocrinidai (a family which 

 in many respects approaches the Neocrinoids more closely 

 than any other Palseozoic forms) possessed the anomalous 

 character of two vaults above the visceral mass — an inner one 

 containing the actinal summit-plates and the covering plates^ 

 like the vault of Platycrinus, and an outer one of a more 

 flexible character and composed of smaller plates belonging to 

 the abactinal system. 



Let us examine into the evidence which has led Wachs- 

 muth and Springer to make this assertion. Neitlier Crotalo- 

 crinus nor Enallocrinus occurs in America; but both genera 

 are found in the Silurian of the island of Gotland, and Crotalo- 

 crinus also occurs in the Dudley Limestone of this country. 

 The National Museums of London and Stockholm contain 

 remarkably fine specimens of these types, but unfortunately 

 they have not been examined by Wachsmuth and Springer, 

 whose knowledge of Crotalocrinus and Enallocrinus is princi- 

 pally, if not entirely, confined to the figures published by 

 Mliller, Angelin, and other authors ; and I have a very strong 

 conviction that the remarkable statement to which they have 

 committed themselves so positively is due to a misinterpreta- 

 tion of these figures. By the kindness of Prof. G. Lindstrora 

 I was able to examine the originals of many of Angelin's 

 figures during a recent visit to Stockholm ; and the examples 

 of Crotalocrinus from Dudley, which are in the National Col- 

 lection at South Kensino-ton, have also come under my obser- 



• • • T 1 1 



vation. These opportunities have convniced me that the 

 " pliant vault " above the summit-plates, which is described 

 by Wachsrautli and Springer in Crotalocrinus, had no existence 

 in reality. They say on pp. 18 and 19 of part iii. : — 



" In the Crotalocrinidte, which include Crotalocrinus and Enallo- 

 crinus, the whole ventral surface, in what appear to be the best- 

 preserved specimens, is composed of strong convex plates, without 

 deiinite arrangement. In these specimens there is no central piece, 

 nor proximals, nor traces of ambulacra (Icon. Crin. Suec, pi. 7, 

 fig. 3 o ; pi. 8, tigs. 6, 7, and pi. 25, tig. 2) ; there are, however, 

 other tigures of Angelin, apparently of a closely allied species (Ibid, 

 pi. 17, tig. 3 o), in which the plates paving the ventral surface are 

 much more delicate, and consist of a central plate, large proximals, 



