420 MURICID^. 



appearance. The embryos of these two species must there- 

 fore differ as much from each other as those of jP. Turtoni 

 and Normgicus. The shell of F.propinqum is rather more 

 tumid, and the whorls rather flatter in the middle, and 

 more raised towards the suture than in i^. gracilis : the 

 strife also are closer, the aperture more contracted towards 

 the canal, and the latter a little more bent" (Alder). 



" A variety from deep water (Ann. Nat. vol. xix. 

 pi. 10, f. 5), is shorter in the spire, and more tumid in the 

 body -whorl, and has the canal very much twisted to the 

 left side. The epidermis is thin, pale yellowish horn- 

 coloured and hispid. The apex is frequently incrusted 

 with black. The animal is white" (Alder). 



Our description of the preceding species will apply like- 

 wise to the present one, except in regard to the apex, 

 which is not oblique and distorted, but symmetrically 

 spiral : the whorls, too, are shorter, scarcely taper above, 

 but are, as it were, more square-cut, standing out from 

 each other in a slightly scalar fashion : the basal declin- 

 ation of the body, likewise, is more flattened. It is much 

 smaller in size, measuring only an inch and a-half in 

 length, and but little more than half an inch in breadth. 

 The ash-coloured epidermis, though spirally ciliated, for 

 the most part, in the young, does not clearly exhibit this 

 feature in adult examples. 



The animal, of which we have given a figure from a 

 drawing by Mr. Alder, is very similar to that of Islmidiciis, 

 but has slender tentacula, and is of a much whiter colour. 

 Its dentition diff'ers ; the axile teeth bear three equal 

 denticulations below ; the laterals have two large nearly 

 equal inner denticles, and one very large outer one. 



We have taken this shell, alive, on sandy ground, in 

 eighty fathoms, off the west coast of Zetland, and it is 



