BUCOINUM. 193 



Dr. Jertroys has narrowed his conception of the species in this 

 instance to suit tlie British specimens which are, as he says, 

 glabrous, without epidermis or any traces of ribs ; the species, 

 liowever. apjjears to attain its maximnm development in the 

 waters of the Athintic coast of British America, and it is from 

 these that our description is made. The ventricoswm of Kiener 

 (hjes not appear to differ. Colored markings are rare upon 

 American specimens — which are almost invariabl}' invested more 

 or less with a very thin epidermis. Our Banks specimens (fig. 

 348) were wrongly identified by Gould and others with B. 

 riliatum^ Fabr., and still are to be found in most of our collec- 

 tions under that name. Stimpson was the first to refer them to 

 B. Humphi^eyfiianum. Of course, there is hardly sufficient 

 character left in the egg-cases alone to justify the adoption of 

 Jeffreys' suggested generic name Mada. 



The zebra-like striped variety {B. ventricosum^ Kiener) is 

 rarely so highly colored as the original figure — which I have 

 copied (fig. 385). B.fusifornie, Kiener (fig. 347), is the typical 

 European form (= glabra, Jeflfreys), and comes from Provence. 

 B. striatum^ Phil. (fig. 349), a Sicilian fossil, is certainly a very 

 good representation of the typical American form. Among the 

 S3aionyms ai'e also to be included B. tumidulum, Sars (figs. 350, 

 351 ), from Norway, and Tritovium ovum, Midd., not Turton (fig. 

 352) ; and probably B. Mo7'chu, Friele, an unfigured species, 

 notwithstanding the more central nucleus of the operculum, the 

 different number of teeth on tlie middle and side plates of the 

 lingual, etc. 



B. Belcheri, Reeve. PI. 77, fig. 353. 



Oblong-ovate, l)ase truncate, thin, whorls convex, linearly 

 spirally sulcate. aperture ovate, columella arcuate, sub-excavated 

 in front, contorted ; livid chestnut within, pellucid ; epidermis 

 thin, deciduous. 



Port Refuge and Dobbin Bay, Arctic Am. (30 fathoms) ; Finmark. 



Like the rest of the genus, this species is subject to great 

 variation. The type specimen is comparatively smooth and 

 without plications beneath the suture ; others are strongly 

 plicated, and have the spiral ridging much raised. Dr. J. Grwyn 

 Jeffi'eys considers it a variety of B, undatum. 

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