134 mproNYX. 



Subfamily Hipponycinae. 

 Genus HIPPONYX, Defrance, 1819. 



Sowerb}', in the first volume of his Thesaurus, has monographed 

 this genus, consisting then of five species, as a bivalve mollusk 

 in connection with Crania and Thecidium, mistaking the occa- 

 sionally formed calcareous base for an attached valve. 



H. ANTIQUATUS, Linn. PI. 40, figs. 93-99. 



White, apex posterior, concentrically rudely, closely laminated, 

 more or less distinctly radiately striated ; epidermis pilose. 

 Length, *75 inch. 



Florida, West Indies, Senegal, Polynesia, 



California, Panama, Peru', Australia. 



The synonyms are H. mitrula, Gmel.; H. Panamensis, C. B. 

 Ad.; H.foliaceus, Quoy (fig. 98), and H. Cfozmas/brwm, Rochbr. 

 (fig. 99). 



H. SERRATUS, Carpenter. PL 40, fig. 100. 



Differs from H. antiquatus in the character of the base of the 

 shell (margin of aperture), which is broad and flat, made up of 

 very numerous close-set lamellae, deeply serrated into large, 

 scarcely rounded lobes ; the interstices are filled with epidermis, 

 in irregular ribband-like shreds. Length. 1 inch. 



Mazatlan. 



Living attached to each other or to other shells. H. foli- 

 aceus, Menke (not Qnoy and Gaimard), is probiibly a 



H. SUBRUFUS, Lam. PI. 40, fig. 1. 



Shell orange or orange-red, decussated by radiating and con- 

 centric close striae. Length, '5 inch. 



West Indies, Peru, Panama. 



H. cernuus, Gmel., is probably identical. 



H. tuberculatus, Carp., is similarly colored, with subcentral 

 apex, close radiating ribs and concentrically tubercnlate, base 

 thick, lamellate. Length, *5 inch. 



Morch refers it here doubtfully. H. trigonus,Gmel., is said to 

 be flatter than subrufus, with stronger radiating sulci, and to 

 this Morch doubtfully refers H. barbatus, var. cosfaUahts of Car- 

 penter; it is perhaps only a variety of subrufus. 



