102 



NOTES 



OiN Foreign Jurassic species of the gknus HEMICIDARIS nearly allied to 

 British forms, but which have not yet been found in the English Oolites. 



Hemicidaris crenularis. Lamarck's (sp.), Goldf., Petrefact., p. 122, t. 40, fig. 6. 



— — Agassiz, Echinod. Foss. Suisse, II, p. 44, t. ] 8, figs. 23, 24 ; 



t. 19, figs. 10—12. 



— — Cotteau, Etudes Ecbinides Foss., p. 122, t. 13, figs. 1 — 9. 



Test globular, flattened at the base, and on the upper surface. Ambulacral areas 

 narrow, and flexuous above ; six pairs of close-set semi-tubercles at the base, and two rows 

 of minute tubercles on the sides, running into one row in the upper part of the areas ; 

 inter-ambulacra with seven or eight large tubercles in each of the two rows. Mouth 

 opening very large, one half the diameter of the test ; peristome deeply incised into ten 

 nearly equal sized lobes. Apical disc small. 



Spines large, thick, claviform, gradually increasing in thickness from the head to the 

 distal extremity; surface covered with longitudinal lines. The largest spines are once and 

 two thirds the length of the diameter of the test ; milled ring small, stem without any 

 apparent neck. 



The greater size of the mouth opening, the depth of the notches in the peristome, the 

 greater equality in the size of the lobes, with less tumidity at the base of the test, added to 

 the claviform character of the spines, serve to distinguish this species from Hemicidaris 

 intermedia, which in other respects it most closely resembles. 



Dimensions. — 'Height, one inch and one fifth ; breadth, one inch and a half. 



Formation. — Corallien of Switzerland, and of France. 

 Coral Rag, Nattheim. 



Collections. — In all Foreign Collections of Jurassic Fossils. 

 British Museum, my Cabinet. 



