1879.] MR. F. J. BELL ON THE ECHINOIDEA. 253 



tubercles in different species, to be a character of value. Thus, 

 in M. grandis there are lar^e and distant tubercles, not only 

 within the peripetalous fasciole and in the anterior ambulacra, but 

 also over very nearly the whole of the actinal surface. In M. ven- 

 tricosa the large tubercles on the abactinal surface are much rarer, 

 and there are, especially along the ambitus, smaller and more 

 closely packed tubercles ; the larger and more distant tubercles 

 are confined more to the anterior end of the actinal surface than they 

 are in M. grandis. In Brissus the large and distant tubercles are 

 completely absent from the posterior end of the abactinal surface, 

 while on the same surface in Metalia the large tubercles are con- 

 fined within the peripetalous fasciole ; and, further, in Metalia ster- 

 nalis they only occupy the margins of the interambulacra. 



The example of M. ventricosa in the Museum collection is parti- 

 cularly fine. Though obtained in April 1847, it does not figure in 

 Dr. Gray's Catalogue (1855). It was registered under the name of 

 Amphidetes (sic) gigas, and is reported to have come from Brazil. 

 I found some difficulty in determining it until I lit on the elegant 

 diagnosis given by Prof. Grube of Brissus panis^. As to the identity 

 of the British-Museum specimen with B. panis of Grube I have no 

 doubt ; the subjoined details will show some points of resemblance. 

 I add some measurements of Meoma grandis : — 



Meoma ventricosa, Brissus panis. M. grandis. 

 (B.M.) (Grube.) (Gray's type.) 



millim. millim. millim. 



Long axis 177'5 162 ( = 6 German 115 



inches) 



Transverse axis 152 135 ( = 5 G. i.) 103 



Height 82 81 (=3 G. i.) 51 



Anterior pair ambulacra 80*80 .. .. 51-53 



Posterior „ „ 9 J "88 .. .. 5960 



Length of anal system 21 .. .. 17'5 



Breadth „ „ 17 .. .. 15 



I am not inclined to dispute Liitken's view of the identity of 

 Grube's species with Meoma ventricosa, Lamarck. The number of 

 spines preserved on the specimen is fairly good ; of those on the 

 abactinal surface I found the greatest length to be about 8 millims. ; 

 but I measured one on the actinal surface which reached 12 millims. 

 (Grube's longest spine measured 3 lines). The spines on the ambu- 

 lacra are somewhat longer and thicker than those on the interambu- 

 lacra, and are so set horizontally as to bridge over the ambulacral 

 grooves ; they are in all cases of a whitish colour, and are not pro- 

 duced into sharp points. The madreporic plate is not less porous 

 than in M.gratidis. Grube had no information of the locality of his 

 specimen ; the most southern locality given by Agassiz is Honduras. 



1 Grube : " Diagnosen einiger neuen Ecbinodermen," Arch. f. Nat. 1857, 

 pp. 340-344 ; " Beschreibungen neuer oder weniger bekannten Seesteme und 

 Seeigel," Nova Acta, torn, xxvii. (Jena, 1860). 



