MUSEUM OF COMPAIIATIVE ZOOLOGY. 253 



Ccrithiopsis Kmcrsonii 11. & A. Adams, Gen. liec. Moll., I. p. 210, 1858. Binney's 

 Gould's Inv., p. 887, fig. 049. Verrill, Kep. Inv. Vineyurd Sound, p. 048, 

 pi. xxiv. fig. 151, 187;J. 



Habitat. Cape Cod southward to the Antilles. Station 247, off Grenada, 

 dead, in 170 fms. 



The Trochus punclalus of Linnd is admitted by Ilanley and Desliayes to be 

 unrecognizable. riiilij)pi tliouglit he recognized it in our American shell. 

 Others have followed him, including Tryon. If there were nothing else in the 

 way, we might recognize the name as of Philippi, o])jectionable and wholly 

 inap})licable as it is if the meaning of the word be considered. But Linne 

 staled that his shell came from South lilurope; Hanley intimates that it was 

 a variety of C. tuhercularis, and Brugiere described an identifiable Cerilhium 

 }mnctatum long before the publication of Philippi. 



The first name recognizable as belonging to our species was given by Mon- 

 tagu, under the supposition that the shell was British. In this way a number 

 of Antillean species were first described. Since we have to give up the famil- 

 iar name of Emersonii, it is fortunate that the new name is appropriate, and 

 there is no necessity for resorting to guesswork in order to fix an unsuitable 

 name npon our shell. 



The southern specimens are lighter colored, except the base, which is visible 

 in the purple brown line which distinguishes the suture in fresh specimens. 

 As we go northward, the specimens are ruder and more olivaceous. By a 

 study of the nuclei I have become convinced that they are little, if at all, less 

 variable than the rest of the shell. Considerable variations do occur in the 

 sculpture, size, and prominence of the nuclear whorls. The reliance of some 

 authors on the nuclear characters, as something fundamentally constant, is 

 certainly ill founded. 



I have figured the specimens from Grenada as an example of the elegance 

 of tropical individuals of this species, and the contrast of its tints is not less 

 attractive than its sculpture. 



The soft parts and dentition of this species have been examined by Stimpson, 

 whose drawings and notes are in my hands. They indicate that the external 

 appearance of the animal is much like that of Cerithiopsis tuhercularis given 

 by Jeffreys, previously cited, except that the foot is broader and shorter, and 

 the tentacles more slender and acutely pointed. The operculum of C. suhulata 

 is paucispiral, of three whorls, thin, horny, and externally concave. The ele- 

 ments of the jaw are partly scale-like, and partly raised and pointed. But the 

 dentition is quite peculiar. The median tooth is wide, with a narrow five- 

 toothed cusp, and a cusp-like projection from the middle line of the base. The 

 major lateral is extremely w^ide and short, its outer portion slightly curved and 

 simple, the inner part with eight or nine small denticles; subequal, like those 

 on the median tooth. The outer laterals, two in number, are long and narrow, 

 the base notched, the cusp suddenly narrowed like a claw, and the inner edge 

 of the claw with five or six fine denticulations. 



