46 FURTHER ADDITIONS TO THE TASMANIAN MOLLUSCA, 



is here slightly hollowed. Whorls 3, the spire very small, 

 and but little excerted. Aperture lunate; outer lip 

 rounded, somewhat thickened; columella slightly concave, 

 flattened, expanding above into a broad callus, which 

 partly covers an ample umbilicus; this latter is bounded 

 anteriorly by a low, rounded rib, which arises from, a ad 

 causes a thickening of, the columella. Diameter, major 

 5.5, minor 4.5, height 5. mill. 



Locality— Type, with four others, from 40 fathoms, off 

 Schouten Island; also in 50 fathoms, off Maria Island, 

 three specimens. The operculum is at present unknown. 

 This species has a superficial resemblance to several of our 

 smaller Australian Naticas, but differs in its depressed 

 form, colour ornamentation, and particularly in the pecu- 

 liar form of the columella callus. 



It is a very close ally of N. Australis, Hutton, from 

 New Zealand, but that species has a narrower umbilicus, 

 a more produced spire, and lacks the colour pattern. 



CERITHIOPSIS TRISCULPTA, Sp. Nov. 



PI. II., fig. 4. 



Shell very small, pyramidal, solid, grey-brown ; whorls 

 six, rounded, including a pullus of two and a half turns, 

 of which the first is perfectly smooth, followed by strongly 

 sculptured axial ribs, separated by fairly wide interspaces 

 which are sjoirally lirate. 



The adult sculpture commences abruptly, and consists 

 at first of two nodulous keels ; a third keel develops and 

 continues on the lower whorls. There is a small sutu.ral 

 thread, which shows on the body whorl rs a strong, round- 

 ed, smooth keel. The rows of nodules are separated by a 

 deep groove, across which they are connected by a small 

 sunken ridge. The base of the shell is smooth. Aperture 

 subquadrate, curving round anteriorly to a short, open 

 canal ; outer lip rounded, dentated by the sculpture ; co- 

 lumella much curved. Length 2.3, breadth 1. mill. 



Locality — Type, with 4 others, from the collection of 

 the late Mr. Frank Harrisson, and probably from the Der- 

 went Estuary, but the exact locality is uncertain. 



This is a remarkable little shell, with very bold sculp- 

 ture, and unlike any other species known to me. 



