MUSEUM OF COMPARATIVE ZOOLOGY. 275 



Gray, I am also inclined, from a careful comparison of the figures of Gray, 

 to consider as identical with Meoma nigra (Kleinia nigra A. Ag.), as the 

 locality quoted by Gray is undoubtedly erroneous, Captain Belcher, as 

 Liitken mentions in his " Bidrag," having visited Central America; and the 

 fact that we have in the British Museum, brought back by Belcher, an 

 Agassizia subrotunda Gray, and a Meoma grandis Gray, marked "Aus- 

 tralia," neither of which can be distinguished from Agassizia ovulum and 

 Meoma nigra, found upon the West Coast of Central America, seem to 

 indicate without much dcubt an error in the localities of the specimens of 

 Gray's Catalogue. 



Littoral, to 85 fathoms. 



Plagionotus pectoralis Ag., Agass. Cat. Rais. 



Syn. Plagionotus pectoralis Lutk., Bidrag. 

 Gray, Cat. 

 " Desorii Gray " 



" Holmesii, Ravenellianus McCr., PI. Foss. S. C, PI. 3, 



figs. 2, 3. 



I am unable to appreciate the grounds upon which Gray distinguishes P. 

 Desorii Gr. from P. pectoralis Ag. The figure he quotes as basis for his 

 species is taken from the original Spatangus pectoralis Lam., which came 

 from Bahia. 



The identity of the pliocene and post-pliocene species here cited, as well 

 as in the synonymes of the preceding and following species, is of course 

 problematical ; yet the differences indicated by McCrady do not indi- 

 cate as great a range of variation as we find in living species. I have 

 quoted the figures for the sake of calling attention to them. There 

 are, in addition, other tertiary species described by Michelin and by Guppy, 

 coming from the Gulf and the West India Islands ; but as those represented 

 in our collections are not accompanied by figures, I have not attempted to 

 point out their affinities. 



Littoral and fragments from 115 fathoms. 



Brissopsis lyrifera Ag., Agass Cat. Rais. 



The only difference to be traced, after a careful comparison, between 

 Florida and European specimens is the existence of a distinct branch of the 

 subanal fasciole extending round the anal system to the peripetalous 

 fasciole. In European specimens there are traces of this branch, but it is 

 not distinctly and sharply defined as in the Florida specimens. The subanal 

 fasciole seems, from all I can gather after an examination of Spatangoids 

 in various stages of growth, the only one subject to changes, and it is not 



