Trivia.] GASTROPODA. 301 



2+1+1+1 + 2 ; the central and lateral teeth, tricuspidate or multi- 

 cuspidate ; the marginals very variable, hooked, simple or denticulate. 

 Jaws corneous. No operculum. 



Shell ovate, varying from cylindrical to pyriform, sometimes ribbed 

 or pustulate, but mostly smooth, and possessing a high polish and 

 brilliant colouring ; spire nearly, if not entirely, covered by the body- 

 whorl, which envelops it ; aperture nearly central, narrow, and longi- 

 tudinal ; lip and columella more or less toothed the entire length ; 

 occasionally, but rarely, without teeth. 



Genus 1. TRIVIA, Sowerby and Gray, 1832. 



Trivia, S. & G., Conch. Illustr. & Descr. Cat. Shells, by Sowerby, jun., and 

 Gray, 1832, 13. Type : Cyprcea europcea, Montagu. 



Animal with the mantle-lobes approaching on the back of the 

 shell ; the ocular pedicels short. Radula with the central tooth 

 multicuspidate, with a simple base ; lateral teeth arcuate, with a 

 denticulate margin ; marginal teeth narrow, simple, slightly arcuate. 



Shell usually small, transversely ridged, and frequently marked 

 by a depression running antero-posterioiiy across the dorsal region ; 

 whorls of the spire submerged, but may often be traced through their 

 thin outside covering ; anterior channel not prolonged, wide, and 

 slightly reverted ; front of columella internally concave, ribbed. 



Distribution. Warm and temperate seas. 



Fossil. Tertiary. 



1. Trivia australis, Lamarck, 1822. Plate 46, figs. 3, 3a. 



Cyprcea australis, Lam., A.s.V., vii, 1822, 404. Trivia australis, Lam., 

 Voy. Astrol., iii, 48, pi. 48, f. 19-26 ; Conch. Icon., Cyprsea, iii, pi. 24, 

 f. 138 ; Chemi, Man. Conch., i, 270, f. 1734 ; Thes. Conch., iv, 45, pi. 325, 

 f. 439, 440; Man. Conch. (1), vii, 206, pi. 23, f. 53, 54; Chall. Rep., 

 xv, 427. Cyprcea rosea, Duclos : Potiez, Gall, des Moll., 1838, 477. 



Shell small, ovate, slightly narrowed in front, rather thin, with a 

 few brown spots on the back. Sculpture consisting of fine transverse 

 costse, interrupted on the dorsal surface by an impressed median line, 

 more prominent near the aperture, and continued over the outer lip 

 and the columella. Colour pinkish-white, with a few brown spots 

 of various size on the back, the extremities tinted with rose, base 

 white. Protoconch minute, usually hidden, but visible through the 

 thin' covering, of 2 narrowly-coiled-up smooth and convex whorls. 

 Aperture narrow, curved at both extremities. Outer lip rounded, 

 elevated beyond the apex, denticulated. Columella flattened, deeply 

 excavated in front. 



Diameter, 10 mm. ; length, 1-1 mm. 



Animal figured in Voy. Astrol. 



Type in the Mus. Hist. Nat., Geneva. 



Hob. Cape Maria van Diemen ; Whangarei Heads (C. Cooper) ; 

 Hauraki Gulf ; Chatham Islands ; Te Mahia Peninsula ; Cook Strait. 

 More common in Australia and Tasmania. 



