MOLLTJSCA OF THE ' CHALLENGER ' EXPEDITION. 341 



MoLLFSCA 01' H.M.S. ' Challenger ' Expedition. — Part XX. 

 By the Eev. Eobeet Boog Watson, B.A., F.E.S.E., F.L.S. 



[Published by permission of the Lords Commissioners of the Treasury.] 



[Eead June 21, 1883.] 



Earn. BuLLiD^ {continued). Earn. Apltsiid^. 



The group belonging to these two families, so far as already 

 overtaken, is a small one, comprising only three genera with five 

 species. All the species, however, are of great beauty and 

 interest. 



Fam. BuLLiDiE, Stol. 



1. Gen. Atys. [ 2. Gen. Scaphander. 



Atts, Montf. 



Atys htalina, n. sp.* 



July 29, 1874. Levuka, Fiji. 12 fms. 



St. 186. Sept. 8, 1874. Lat. 10° 30' S., long. 142° 18' E. 

 "Wednesday Island, Cape York, JN". Australia, 8 fms. Coral- 

 sand. 



St. 187. Sept. 9, 1874. Lat. 10° 36' S., long. 141° 55' E. 

 Near Cape York, IST. Australia. 6 fms. Coral-sand. 



Shell. — Oval, subgibbous, a little abruptly contracted and 

 slightly constricted and truncated above, striated, thin, hyaline, 

 umbilicated, with a largish curved mouth. Sculpture. Longi- 

 tudinals — there are very many slight equal hair-like lines of 

 growth. Spirals — with the exception of a narrow nearly median 

 band, which is smooth, the whole surface is scratched with fine 

 smooth regular square-cut widely parted furrows. These are 

 rather more regularly arranged above than below, where the 

 interstices are more wide and less regular ; but toward the end 

 of the shell in both directions the furrows tend to become 

 crowded ; they extend to the very edge of the funnel-shaped de- 

 pression of the apex ; but the 'depression itself is smooth except 

 for the twisted edge of the outer lip, which is reverted as usual, 

 but somewhat narrowly at the generic sinus : in front they score 

 the umbilicus on one side, but do not quite extend to the edge 

 of the pillar. Colour hyaline to translucent. Mouth long, curved, 

 rather narrow, and not much enlarged in front. Outer Up convex, 



* Not Bidla hyalina, Gm. 

 LINN. JOFEN. — ZOOLOGY, VOL. XVII. 25 



