a Genus of qtumparasitic Mollusks. 825 



a dozen specimens of the shell which he had thus provisionally 

 named in the crevices of Madrepores and other stony corals that 

 had been collected on the shore of one of the West-India Islands 

 for the purpose of being burnt into lime, and had formed part 

 of the ballast of a vessel bound to Europe. As the corals had 

 lain on the beach for a long time, Chemnitz thought the shells 

 might have been terrestrial, and not marine. Mistakes of a 

 similar kind have been made by modern conchologists — e. g., 

 Halia Priamus. 



M. Hupe, the able and courteous curator of the natural-history 

 collections in the Jardin des Plantes (whose knowledge of the 

 recent Echinodermata is very extensive), published in the 

 ' Revue et Magasin de Zoologie' for March 1860 a description 

 of another species, under the name of Sti/lifer Orbignyanus, 

 While examining a specimen of Cidaris imperialis, Lam., from 

 New Holland, he noticed that two of the spines were unusually 

 enlarged, tumid, and irregularly spherical ; at their base he ob- 

 served two small vertical slits, like button-holes, placed opposite 

 to each other. A section of these spines showed that in the 

 cavity of one was enclosed an adult Stilifer, and in the other, two 

 specimens, which were also adult, besides several embryonic shells. 

 With respect to the mode by which the Stilifer had thus be- 

 come enclosed, M. Hupe was of opinion that the cavities were 

 not made by them, but that the interposition of some part of 

 the mollusk had prevented its being completely imprisoned in 

 the spine during the progress of the growth of the Cidaris, 

 which would otherwise have enveloped and smothered the Stili- 

 fer. He was kind enough to show me the specimens ; and 

 they seemed to present an analogous case to that of Stilifer 

 astericola, which I had examined in Mr. Cuming's collection. 



Lastly, I would cite an excellent monograph by Dr. Fischer, 

 which appeared in the * Journal de Conchyliologie ' for April 

 last, on the genera Stylifer and Entoconcha (p. 91 &c.). In this 

 monograph all the known species of Stilifer are redescribed, and 

 a new one (-S'. Pauluccia) well described and figured. According 

 to Fischer, the Entoconcha mirabilis of J. MUller, found in 

 Si/napta at Trieste, is probably the fry of some other mollusk. 

 At all events, we want more information about it. * It is almost 

 microscopic. 



But to return to Stilifer. Fischer suspected that it is not a 

 true parasite. He says that the discovery by M. Hupe proves 

 that, although living like a parasite on the tegumentary system 

 of the Echinoderms or their appendages, the Stilifer does not 

 feed on their substance, as has been supposed. Its nourish- 

 ment comes with the sea-water through the openings of the 

 cavity which it occupies: perhaps its proboscis may be pro- 



