MOLLUSCA OF THE ' CHALLENGES ' EXPEDITION. 253 



pressed suture. Apex consists of I5 smooth, globularly rounded 

 wliorls, the extreme point of ^Yhich has the slightest possible 

 prominence. Whorls 7g-S, of very slow increase, short, tlae last 

 scarcely more tumid than the rest, with a contracted conical base 

 and a shortish snout ; they are angularly convex, with a slight 

 contraction into the suture both at the top and bottom of each 

 whoi'l. Suture : there is a minute angular impression at the line 

 of suture, which is marginated below and is made yet more distinct 

 by the contraction of the whorls above and below. Mouth pear- 

 shaped, small, with a slight angulation above and a rather wide 

 and open canal below. Outer lip forms a regular curve, steeper 

 above, and more drawn out below towards the point of the shell ; 

 on leaving the body it retreats, at once and very much, to the 

 left ; after forming a shallow, open, rounded sinus, it advances to 

 the right and forward as a small low- shouldered pinion, re- 

 treating along the edge of the canal to the point of the shell. 

 Inner lip narrow, slightly sunken, so that the surface of the shell 

 slightly projects at the edge of it; its line across the body is 

 straight, being neither convex nor concave. The pillar is narrow, 

 strong, and very short, being obliquely cut off early, with an 

 angularly rounded, slightly twisted edge and a backward trun- 

 cated point. H. 0'3. B. O'll. Penultimate whorl, height 0'05. 

 Mouth, height 0-1, breadth 0-07. 



This is another of that curious group which, have a tendency to 

 a cylindrical form, a long spire, many short whorls, a broad apex, 

 and a short base. 



I have with some hesitation united to this species as a var. platia 

 (TrXarvs, broad) the specimens from St. 122. As the name indi- 

 cates, they are broader in proportion to height ; they are also less 

 cylindrical, the embryonic whorls in particular, the tip being rather 

 smaller and the basal part of the apex broader ; the threads on 

 the base of the shell are weaker. On the other hand, the whole 

 form of the whorls and the details of sculpture are identical. 

 In these circumstances it is probably wiser to unite them all in 

 one species, attributing the differences partly to habitat and 

 partly to the specimens of the variety being not fully grown. 



70. Pleurotoma (Clionella) quadeuplex, n. sp. 



St. 73. June 30, 1873. Lat. 30° 30' N., long. 31= 14' W. 



