MOLLTJSCA OP THE ' CHALLENGER ' EXPEDITION". 33 



slightly broader in front ; its side slopes are slightly, its front 

 slope extremely convex, its back slope is short and flattened and 

 very much overhung by the protuberant apex ; there are sparse 

 and distinct riblets. The slit is short and coarse, though not 

 large ; and from it a broad round ridge trending to the right 

 runs out to the margin. Sculpture. The riblets are neither 

 strong nor sharp ; but they are distinct, rising as little round 

 threads from the flat surface, and being parted by broad intervals, 

 rather strongly pitted by the little specks of the genus; the 

 ridge vrhich runs down the front of the shell is the full breadth 

 of the slit ; the concentric striae are mere slight irregular lines of 

 growth. Colour clouded, porcellaneous white under the brownish 

 caducous epidermis. Apex very much curled in and bent down, 

 but not spread out on the backward slope ; the minute extreme 

 tip is exserted and projects ; the whorls are 2|. Slit : the open 

 part is short and narrowly oblong, and as broad in front as 

 behind, from which point the old scar runs up the crest. Margin 

 thin, patulous, especially behind, crenulated by the riblets. 

 Inside porcellaneous, deeply hollowed into the apex ; scored by 

 the rib-furrows, of which the one in front is very strong, particu- 

 larly near the slit, which is rather closely covered by the strong, 

 slightly arched septum, which has a retracted edge and is un- 

 buttressed. L. O'lS. B. 0-12. H. 0-1. 



In the animal the eye-peduncles are present ; but no eyes are 

 visible ; the pedal papillae are very small, as is also the funuel- 

 shaped process leading to the shell-slit. 



This species in general form is a good deal like P. agger, but 

 is more tumid and higher ; the apex and sculpture are very dissi- 

 milar. Than P. conica, d'Orb. {Rimula), which is much of the 

 same size, P. hrycMa has the apex much more turned over ; the 

 form is broader and much more depressed. 



5. PUNCTTTBELLA n. Sp.(?) 



Sept. 7, 1874. Torres Straits. North of Australia. 3-11 fms. 



Sept. 8, 1874. Torres Straits. Flinders Passage, North of 

 Australia. 7 fms. 



St. 186. Sept. 8, 1874. Torres Straits. Wednesday Island, 

 North of Australia. 8 fms. 



St. 187. Sept. 8, 1874. Torres Straits, Cape York, North of 

 Australia. 6 fms. 



This species, which I believe to be new, is peculiar from its 



LINN. JOUEN. — ZOOLOGY, VOL. XVII. 3 



