104 AMERICAN MARINE CONCHOLOGY. 



grooved ; outer lip arching forward : inner lip with a thin coat of 

 enamel, with a single oblique fold or small tooth near the base ; 

 whitish, immaculate. 



Length 2.5 to 5 mill. 



Neio Eiifjland; South Carolina. 



3. TJ. BiPLiCATUS, H. C. Lea. Fig. 213. 



(Bulla.) Proc. Bost. Soc. Nat. Hist., 204. 1844. 

 Shell c^'lindrical, siibquadrate, thick, whitish, polished, ivory- 

 like ; spire concealed ; last whorl with a callus above, and small 

 transverse stripe below; mouth narrow above, ovate below ; colu- 

 mella with a large and a small fold. 



Cape May, N. J. 



Genus DIAPHANA, Brown. 

 Conch. Text-Book, 113. 1833. 



Head-disk broad and short; tentacular lobes short, conical, 

 lateral, wide apart; eyes immersed in tlieir bases behind; mantle- 

 margin slightly thickened ; foot short, bilobed behind. 



There are but few species, of northern distribution. 



1. D. HiEMALis, Couthou3\ Fig. 214. 



iBulla.) Bost. Journ. Nat. Hist., ii. 180, t. 4, f. 5. 1839. 

 Utriculus globosus, Loven, Ind. Moll. Scand. 1846. 



Shell globular, very thin and brittle ; the bodj'-whorl envelop- 

 ing all the others so as to leave no perceptible spire, and marked 

 with the lines of growth ; aperture narrow above, dilated be- 

 neath ; outer lip strong, and regularl}^ curved ; It revolves from 

 its junction behind nearly a third of a revolution before it turns 

 forward; columella slightly arcuated and reflected upon the body 

 of the shell so as to form a small but distinct umbilicus ; hyaline, 

 with brownish tinge. 



Length 2.5. mill. 



liew England, northioards. {Eur.) 



2. D. HYALiNUS, Turton. Fig. 215. 



{Utriculus.) London's Mag. Nat. Hist., vii. 353. 1833. 

 Bulla debilis, Gould, Am. Jonrn. Sci., xxxviii. 19G. 1840. 



Shell small, obliquely ovate, tumid, thin and brittle; whorls 

 four, all rising to tjie same height, convexl}^ rounded ; last whorl 

 the whole length of the shell ; surface smooth ; aperture as long 

 as the shell, widening below, outer lip slightly waved, inner lip 



