ACLIS. 221 



Montagu had proposed to call Turho perforaUis. In 

 general, tlie surface as it is found in cabinets is worn to a 

 state of smoothness, in these the sculpture is most distinct. 

 The shape is turreted-subconical, the spire rapidly taper- 

 ing to a very fine point, which, however, is not simple, 

 but distorted, as in the Chemnitzife. The shell is thin, 

 glossy, slightly translucent, and of an uniform white ; its 

 earlier volutions (the apical ones excepted) are adorned 

 with three narrow spiral ridges, which in one of our 

 examples continue throughout ten of the coils, but more 

 frequently are visible upon three or four alone ; indeed, 

 from the abrasion of the majority of specimens it is difficult 

 at times to perceive more than the traces of their former 

 presence. The upper third at least of the ridged volutions 

 is quite smooth, as are likewise the narrow intervals of the 

 costellse ; there seem, however, vestiges, in certain exam- 

 ples, of some obscure longitudinal pliciform wrinkles upon 

 the posterior portion of some of the last formed turns. In 

 our largest specimen, which measured three-tenths of an 

 inch in length, and about one-tenth in breadth at the base, 

 we counted twelve whorls : they are moderately rounded, 

 short, of rather quick lateral, but slow longitudinal en- 

 largement, slightly more tumid below than above, and 

 divided by a profoundly impressed but not canaliculated 

 suture, which is, perhaps, rather less oblique than in the 

 majority of shells. The basal declination of the body is 

 rounded, but rather abrupt ; the body itself is swollen, but 

 so far horizontally compressed (not flattened), on the 

 ventral side, as to show a kind of excavated space behind 

 the pillar leading to the very large and open umbilicus, 

 which perforation is, however, disproportionately small in 

 the immature examples. The mouth, which occupies 

 about two-sevenths of the total length, has a rounded oval 



