402 RET. It. B00G WATSON ON THE 



upper side, but becomes large (though hardly deep) from the great 

 forward wing-like sweep of its lower margin, whose course is 

 quite independent of the ribs ; toward the edge of the canal this 

 curve again retreats to the point of the shell. Inner lip is a thin 

 narrow glaze margined with a minute furrow ; it is oblique, but 

 scarcely convex across the body, direct on the short pillar, and 

 cut off w r ith a long slope to the point of the canal, its edge being 

 narrow, rounded, and scarcely at all twisted. H. 0*43. B. 017. 

 Penultimate whorl, height 0*07. Mouth, height 0*2, breadth 

 0*08. 



This species may be associated with the P. nivalis, Loven, 

 group ; for though very unlike in texture of shell and length of 

 mouth, yet the general form and st}de of ribbing are somewhat 

 similar. 



11. Pleitroxoma (Surcula) bolbodes, n. sp. (/3oA/3w3»}S, 

 from its bulbous apex.) 



St. 120. September 9, 1873. Lat. 8° 37' S., long. 34° 8' W, 

 Pernambuco. 675 fms. Mud. 



Shell. — High, narrow, conical, with a large bulbous apex, a 

 contracted conical base, and a long snout ; scarcely carinated, 

 ribbed, with spiral threads, an impressed suture, pale buff. Sculp- 

 ture. Longitudinals — the whorls are crossed from suture to suture 

 by ribs, which are a little oblique and not curved ; they are nar- 

 row, pinched in laterally, and most prominent a little above the 

 middle of the whorls ; they do not extend to the base, they are 

 parted by shallow furrows rather wider than themselves ; on the 

 last whorl there are twelve, and they increase in number up the 

 spire ; those at the top are a little sinuous and crowded. The 

 lines of growth are very faint, except on the base. Spirals — there 

 are about ten rounded prominent threads on each whorl, which 

 stand out with special prominence on the ribs ; on the last 

 whorl these continue with very considerable regularity and equa- 

 lity to the point of the shell ; in the constriction below the 

 suture they are feeble. Colour pale buff, but probably white in 

 the living shell. Spire conical, not much contracted ; the first 

 regular whorl is exceptionally tall, narrow, and cylindrical. 

 Apex is a coarse swoln small bulb of little more than one smooth 

 whorl, which lies very much on one side, with the extreme tip 

 almost bent in under it. Whorls 6, high, of slow increase, the 

 last a very little tumid j in the sinus-area they scarcely expand. 



