164 M. o. A. L. morch's review of the vermetid^. [April 9, 



Var. a, costulis cequalibus, circiter 12-14, approximatis, asperis, 

 oblique tortis, prcesertim in regione umbilicali, ubi squaniiferce ; 

 apertura circularis leviter constricta. 



Var. /5, carina mediana prominente. 

 Diam. apert. 5 m. 



T. juvenilis Candida crystallina, pallide fiisco tincta, verruds 



cylindricis munita (Algir. Guyon, Mus. Reg.). 

 On Spoiuhjlus gcederopus: probably from Spain. 

 The young shell is of a white, chalcedony-like appearance. 



19. SiPHONIUM LURIDUM, Morcll. 



T. contorta, tenuiiiscula,subdiaphana, pallide lurida; anfr. teretes, 

 rapide crescentes, soluti, angulatim contorti, longitiulinaliter 

 striati et lirati; lirce prominulce, circiter 20, squamis fornicatia 

 compressiusculis, prcesertim aperturam versus, validis, interdum 

 transversim confiuentibus ; strioB incrementi in interstitiis cos- 

 tarum leviter arcuatce; anfr . primi graciles, laqueati, albi, sculp- 

 tura evanescent e ; apertura circularis, soluta, faucibus strata 

 tenuissimo sericeo obteciis. 

 Diam. apert. 18 m. 

 Hab. Society Islands (coll. Cuming.). 



The colour and sculpture remind one of certain varieties of Pinna 

 pernula, Ch. The longitudinal flat and feeble lircB are almost obsolete 

 on the scales ; there are about three to six between the keels. The 

 inner thin layer scarcely conceals the outer brown colour. Some of 

 the keels show small indistinct white spots. The sculpture on the 

 infero-marginal side is entirely rubbed out, and shows the cast of 

 some foreign body : on one of the first whorls are distinctly to be 

 seen the cast and rests of the cells of a Bryozoon. The lid is un- 

 known, and the genus of course a little doubtful. 



20. SiPHONIUM MARGARITARUM, Val. 



Vermetus mar garit arum, Val. Voy. Venus, pi. 1 1. f. 2 (the larger). 

 Vermetus margaritaceus, Rouss., Chenu, 111. t. 4. f. 2 (the same). 

 Aletes margaritarum. Carp. Cat. Reigen, p. 303. 

 Siphonium margaritarum, Morch, Journ. Conch. 1859, p. 359. 



Hab. Panama (Fa^.) ; Mazatlan (JRe^$rem). 



I refer this species to the genus Siphonium, on account of the cir- 

 cular mouth, and some likeness to the much smaller S. nebulosum, 

 Dw. The lid is unknown. In Mr. Cuming's collection there is a shell, 

 without locality, very like the quoted figure ; but the aperture is 

 much higher than broad, of an oblong trapezoid shape, and the 

 outer basal angle of the aperture is very sharp, while the upper is 

 obtusely rectangular (alt. max. obliq. 22 m., lat. 14 m.). In the in- 

 terior is a broad blackish basal band spreading on the sides like that 

 of (S. nebulosum, but broader. This shell will very likely prove to 

 be generically distinct, as all the specimens of Siphonium 1 have seen 

 have a circular mouth, depending on the large operculum. 



