BRITISH FUS8ILS. 



Decade V. Plate X. 



BRISSUS SOILLiE. 



[Genus BRISSUS. Klein. (Sub-kingdom Eadiata. Class Echinodermata. Order 

 Echinoidea. Family Spatangidse.) Body oval or oblong, tumid ; dorsal ambulacra 

 subpetaloid, circumscribed by a peripetal fasciole ; tubercles of dorsal surface all similar ; 

 anus terminal, supra-marginal ; caudal extremity with a sub-anal fasciole.] 



Diagnosis. B. dense tuberculatus {tuber cidis anticis majoribus) oblonyo- 

 ovatus elevatus nec hiflatus, marghii subcompresso ; vertice excentrico ; 

 interambulacro postico plus minusve carinato ; ano verticali; fasciola 

 peripetali anterius sinuata et utraque semel nec bis angulariter inflexa. 



Reference. Scilla^ de Corp. Marin is, pi. 14. f. 2, 3. (Spafangus 

 placenta, Philippi in Erichs. Arcliiv. for 1845, pi. 1. p. 349?) Briss. 

 Scillce, Agassiz and Desok (1846), Ann. Sc. JSTat., 3rd ser. torn. 8. p. 13. 

 Forbes (1852), Pala^-ontograpli. Soc. Trans. (Ecli. of the British Ter- 

 tiaries) p. 15. pi. 2. fig. 4. in Morris's Catal., 2nd edit. (1854), p. 73. 



" This sea urchin, one of the largest and most remarkable of all 

 those found fossil in the crag, varies inucli in proportion, but is 

 distinctly identical witli Scilla's species, which lives in tlie Medi- 

 terranean, and occurs fossil in the Miocene of Malta. I purposely 

 oinit, hovrever, all references to Lamarck, as there is sad confusion 

 about this Brissus and its allies. 



" Description. — The length of our line specimen, presented to the 

 Museum of Practical Geology by E. H. Bunbury, Esq., is inches, 

 breadth 3 inches, height 2J inches. The species A^aries mucli in 

 shape, some specimens being oblong, some wide and ovate ; tlie 

 former are usually high, and strongly subcarinated on the back, 

 the latter are more depressed ; but all have the apex strikingly 

 eccentric, and the cmferior^ extremity abruptly truncated. 



* Probably " posterior " was intended to be written here, but the word is preserved, 

 as it is possible Prof. Porbes intended the steep slope of the anterior end. It can scarcelr 

 be called " truncated," much less " abruptly truncated." — J. ^V. S. 



[v. X.] 5 K 



