228 GJECIBM. 



Torinia, composed of a spiral band ciliated at the margin, forming 

 a cylinder or cone, the axis of which is filled up by a series of 

 spiral radiating cells. 



PYXiPOMA, Morch, 1860. Slit closed by a lamella, but not filled 

 up outside. S. lacteus^ Lam. Australia. 



AGATHiRSES, Moutf., 1810. The band composed of numerous 

 isolated holes. Chiefly fossil. S. squamosa, Lam. 



CRYPTOBiA, Desh. Proposed for a tubular shell, with spiral 

 commencement, formerly supposed to be constructed by an 

 annelid. It is believed to be related to Pyxipoma by Mcirch, 

 but its true nature is bj^ no means clearly established. S. 

 Michelini, Desh. Isle of Bourbon. 



Family CJECIDiE. 



Shell with a fugatious spiral nucleus ; tubular, regular, minute. 

 Operculum horny, multispiral, margin sometimes fimbriated. 



Animal. Lingual membrane short; teeth in two series (2"0*2), 

 central denticles none, the lateral imcini with the inner one 

 broad and serrulated. Rostrum long and flat ; tentacles short, 

 subclavate at the tips ; eyes sessile behind the bases of the 

 tentacles. Mantle thick, fleshy, circular, closely embracing the 

 neck ; a single branchial plume. Foot short, narrow, truncate in 

 front, obtuse behind. Not at all shy, progressing with great 

 vivacity. 



C^CUM, Fleming. 



Syn. — Anellum, Carp. C^ecalium, Macg. Odontidium, Phil. 

 Fartulum and Elephantulum, Carp. Brochina, Gra3\ Corni- 

 culina, Munster. Brochus, Browne. Odontina, Zborzewsky. 

 Dentaliopsis, Clark. Odontidium, Phil. 



Distr. — 42 sp. Europe, United States, West Indies, Mazatlan, 

 Australia, Japan, Mauritius. Fossil, 8 sp. Eocene — . C. cor- 

 nuoides (Ixvii, 81). G. pulchellum, (Ixvii, 82). 



Young shell spiral in one plane, afterwards an arcuated tube, 

 truncated posteriorly by the loss of the spiral portion, and closed 

 there by a convex septum. 



P. P. Carpenter proposed subgenera for species distinguished 

 by diff'erences of sculpture, but M. de Folin, who has recently 

 studied the Ca^cidse, points out that these groups are not founded 

 on permanent characters, the various species exhibiting a series 

 from smooth to ribbed surfaces. 



BROCHINA, Gray. Founded on a single species, and insuflfi- 

 ciently characterized by its convex opei'culum. 



MiocERAS, Carpenter, 1858. Young shell loosely spiral, not in 

 one plane ; adult shell somewhat inflated, aperture oblique ; oper- 

 culum externally concave. The species are all smooth, the 

 adult resembling in shape the horn of an ox. G. cornucopia, 

 Carp. 



