MOLLTJSCA OE THE ' CHALLENGER * EXPEDITION. 227 



Apex small, consisting of two embryonic whorls, perfectly- 

 rounded, not depressed, slightly tumid, hyaline. Whorls 12, of 

 very slow and regular growth, prominent at the keels, but con- 

 tracted above and below and in the middle. The last is round 

 and prominent on the base, in the centre of which it is impressed 

 in an open umbilical pit. Suture very fine and inconspicuous ; 

 towards the end of the last whorl it is very deeply sunk, from the 

 contraction of the outer lip upon the base. Mouth small, rectan- 

 gularly triangular, the right angle being at the base of the pillar. 

 Outer tip advancing a good deal at its junction with the base, and 

 drawn in very much toward the base of the pillar, so that at this 

 point its direction is very nearly at right angles to that of the shell's 

 axis, curving a little, and retreating into the labral sinus ; it here 

 meets the nearly straight line of the patulous and prominent basal 

 lip, which almost forms a sinus at the point of the pillar. Inner 

 lip carried as a thin glaze across the body and round the base of 

 the pillar, so as almost to form an umbilical chink behind it. 

 Pillar perpendicular, straight, with a slight twisted swelling at 

 about one third of its length ; the edge is very thin and narrow, 

 flat, patulous, and projecting at the side of the pillar as a small 

 ledge. H. 035. B. 0-085, least 0-072. Penultimate whorl, 

 height 0-038. Mouth, height 0*053, breadth 0*055. 



This very beautiful little shell has some features which recall 

 Bittium ; but it has a distinct canal at the point of the pillar, 

 and it has the labral sinus of Turritella as well as the peculiar 

 microscopic spiral fretting of the genus, though this feature is 

 very obsolete. It has, on the other hand, some features of strong 

 individual peculiarity which separate it from any Turritella known 

 to me. These are its pure hyaline porcellanous colour, its pecu- 

 liar triangular-shaped mouth, and the Vertagus-like swelling on 

 the pillar-lip, which, however, is not to be fonnd in the earlier 

 stages of growth, as no trace of it appears in the many broken 

 specimens. In general aspect it somewhat resembles Cerithiopsis 

 Jeffreysi, E. Sm. ; but that species is much more attenuated and 

 ends in a sharp apex, has three strong spiral threads, and is 

 longitudinally ribbed. 



8. Turritella. (Torcula) admirabilis, n. sp. 



March 7, 1875. Admiralty Islands, N.E. of Papua. 16- 

 25 fms. 



Shell. — Conical, with a very slight convexity, angulated at the 

 edge of the hollowed base, with a shallow impressed suture ; whorls 



