MUSEUM OF COMPARATIVE ZOOLOGY. 73 



This shell was first named by Martyn, but his name under the system then 

 prevailing was preoccupied. Humphreys's name was unidentifiable, except by 

 Dillwyn, who saw the specimens, and he gave neither description, figure, nor 

 reference, but was the first to mention the West Indies as its true habitat. 

 Perry names it, and gives a description and a better figure than that in Reeve's 

 Iconica, but a wrong habitat. His name should be adopted. Wood's specific 

 name of virgo, adopted by Lamarck, is seven years later in date. The best 

 figure, singularly enough, is that of Guppy, who figures it from the Tertiary of 

 Hayti. 



The species probably lives between the 100 fm. line and the shore. All the 

 specimens above cited from deeper water were dead, and probably disgorged by 

 fishes. The only living ones I have seen were dredged in 2G fms. by the Fish 

 Commission. The operculum is much like that of Conus, long, narrow, strong 

 and thick, rounded behind, pointed in front, with an impressed line running its 

 length parallel with and nearer the right side, which is straighter than the left 

 margin. The nucleus is apical, the area of attachment covers nearly the whole 

 operculum, having a smooth narrow raised border around an impressed space 

 concentrically granosely sculptured. On the right side the raised margin is 

 very narrow. The shell reaches a length of 105 mm. or more, and the typical 

 form has sharp-edged strong spirals, a narrow, flat anal fasciole more prominent 

 than any of the spirals, faint transverse sculpture, and a thick pillar with a ten- 

 dency to become umbilicated. The young shells described by M. Crosse look 

 very different, and only after comparison of many specimens was I able to con- 

 vince myself that Gabb and Try on were right in regarding them as synonyms. 

 The shell is always of a pure yellowish white, without markings, though the 

 apex of the very young is sometimes tinged with reddish brown. The nucleus 

 is inflated, glassy, translucent, of two whorls, which are smooth, then become 

 marked with semilunar riblets which pass into a tubercular keel at the periph- 

 ery which becomes smooth, sharp, and takes the normal character very soon. 



Pleurotoma albida var. tellea Dall. 



This form differs from the normal in having the revolving sculpture fainter 

 and more uniform, the transverse sculpture much stronger and more elevated, 

 giving a finely reticulated appearance to the surface. The anal notch is more 

 shallow, the canal more slender, usually without any umbilical chink. The 

 shell reaches a length of over 100 mm. with a maximum diameter of 26.5 mm. 



Pleurotoma (albida var.?) vibex Dall. 



Shell resembling in a general way the young of P. albida of the same size ; 

 the nucleus is the same, the spiral sculpture resembles that of P. albida but is 

 flat-topped instead of sharp; the transverse sculpture is less prominent, the 

 spirals somewhat more numerous; the chief character which strikes one on 

 comparing the P. vibex with P. albida is that the shell is surrounded with 



