MOLLUSOA OP THE ' CHALLENGER' EXPEDITION. 35 



is almost perpendicular; from it a slight callus encircles the open- 

 ing of the slit. L. 025. B. 0-16. H. 013. 



This species in form somewhat resembles P. a^ffer, but is more 

 long and narrow ; the sculpture and slit are very markedly, and 

 the apex unmistakably, different. In all these respects it differs 

 from P, JSfoachina, L., to the young of which it has a vague resem- 

 blance. That species is also in all stages of growth narrower in 

 front than behind. I failed to recognize either the white or 

 transparent specks, one or other of which are so generally pre- 

 sent in the Mssurellidae. 



7. PUNCTFEELLA PEOFUNDI, Jqffr. [aCUTA, n. Sp.]. 



St. 24. March 25, 1873. Lat. 18° 38' 30" N., long. 65° 5' 30" W. 

 Off St. Thomas, north of Culebra Island, Danish W. Indies. 

 390 fms. Coral-mud. 



Grwyn Jeffreys, * Yalorous ' G-astropoda, Ann. & Mag. N. H. 

 Mar. 1877, p. 232*. 



Shell. — Small, thin, roundly oval ; the front slope is slightly 

 convex, the others still more slightly concave ; the top, of which 

 merely the extreme tip is incurled, projects upwards and a little 

 backwards in a point which is sharpened by the crater-like hole 

 of the slit close in front ; minute riblets closely beaded score the 

 surface ; the slit is large and round. Sculpture. There are very 

 many radiating riblets, which are sharp and distinct but very 

 minute ; the surface is also delicately fretted with fine concen- 

 tric undulations, which in crossing the riblets rise into sharp 

 little contiguous tubercles, but in the narrow intervals are 

 almost invisible. Colour frosted glassy-white. Apex fine, sharp, 

 prominent, projecting upwards and backwards, with only the ex- 

 treme tip (which is very small) incurled and slightly turned 

 round ; there are fully two whorls. Slit is a largish round hole 

 with a pointed prolongation backwards ; it lies close in front of 

 the tip, and cuts away the natural top of the shell. Margin ex- 

 cessively thin, patulous all round, not crimped. Inside glassy ; 

 a very small hollow runs into the apex ; the lines of the outside 

 ribs are just perceptible ; there is no anterior furrow; the slit, 

 as seen from within, is round, and is very little interfered with 

 by the short, thin, triangular, straight-edged, little-oblique* 

 septum. L. 0-21. B. 0-16. H. 0-14. 



* Dr. Gwyn Jeffreys mentions that tliis species was also got by the ' Porca- 

 pine' in 1870 oif the coast of Portugal in from 740 to 1095 fms. 



