190 STILIFERID.f:. 



that mollusk has a denticulated or spinous tongue, and 

 the body is not ciliated. Their habits also are very dif- 

 ferent. Eidima, although allied to the present genus, 

 has a smooth body and an operculum, and it is not pa- 

 rasitic J nor is the apex of its shell style-like or irregular. 

 For the discovery of this cmnous mollusk science is 

 indebted to the indefatigable labours of Dr. Tiu'ton. 

 In the ^Zoological Journal^ for October 1825 an article 

 by him, entitled " Description of some new British 

 Shells," comprised one which he named Phasianella 

 stylifera, and of which he says, " we found a dozen of 

 these beautiful little shells alive, and attached to the 

 spines of the Echinus esculentus, dredged up in Torbay." 

 Not many years afterwards Mr. Broderip made known 

 the peculiar nature of the animal, in consequence of 

 Mr. Cuming having brought home, amongst other con- 

 chological rarities, specimens of another species [S. aste- 

 ricola) burrowing or imbedded in a tropical kind of star- 

 fish. Mr. Arthur Adams subsequently published an ac- 

 count of another species (S. ovoideus) having the same 

 apparently parasitic habits ; and our British species {S. 

 Turtoni) has been repeatedly observed attached to several 

 kinds of Echinus. Another species {S. Orbignyanus) 

 ha\'ing been detected by M. Hupe enclosed in the basal 

 portion of the spines of a Cidaris, which had been en- 

 larged for its accommodation. Dr. Fischer suspected that 

 Stilife?' is not a true parasite, and does not feed on the 

 Echinoderms infested by it. I have come to a similar 

 conclusion, from a careful and long- continued observa- 

 tion of living individuals of S. Turtoni ; and I believe 

 that Stilifer subsists on the excretions of Echinoderms. 

 This opinion is founded on the facts that all the Sti- 

 lifers, British and foreign, which I ha^e seen (and they 

 were numerous) invariably occupied only the area of 



