354 



vol. ix., 1886, p. 100, and listed by Adcock in his Handlist, 

 1893, No. 146. Mr. Hedley has sent me Smith's species, ob- 

 tained from the type locality, and it appears to have less 

 curved dorsal borders and fewer ribs, which are scaled, and 

 not corded. 



It very closely resembles C . eleffantula, Tate and May, 

 of Avhich it may prove to be only a variety, in which case its 

 name will indicate the difference, for it has fewer and higher 

 ribs, with bolder and less crowded concentric cords, and is 

 somewhat less oblique. 



Type in Dr. Verco's collection. 



Carditella vincentensis, n. sp. PI. xvi., f. 20, 21. 



Shell solid, roundly trigonal. Umbos projecting, ap- 

 proximate, curved forward. Dorsal borders converge at about 

 a right angle; posterior straightly convex, anterior slightly 

 excavate. Lunule elongate-cordate, depressed, smooth, its 

 centre prominent, and seen as a convexity in the profile of 

 the shell. Escutcheon well marked, elongate, bevelled edges, 

 left valve overlapping the right. Twenty-two flattened 

 rounded ribs, the posterior straight, the anterior concave for- 

 wards, interstices linear. Well-marked concentric lirse cross 

 the ribs and spaces. Right valve has a central triangular 

 cardinal tooth, a long anterior lateral tooth separated from 

 the margin by a groove, and a thin posterior marginal lateral. 

 The left valve has two diverging cardinal teeth, a posterior 

 lateral separated from the margin by a groove, and an an- 

 terior marginal lateral tooth. The lateral teeth and sockets 

 are microscopically vertically striate. Ventral border well 

 denticulated internally. Colour white, reddish-brown tint 

 on the posterior third of the shell, deepest at the posterior 

 inferior angle. 



Dim. — -Antero-posterior diameter, 3 mm.; umbo-ventral, 

 2-85 mm. 



Hah. — Gulf St. Vincent, Spencer Gulf, and Backstairs 

 Passage, 20 and 22 fathoms, several alive and many valves.. 



Variations. — The posterior dorsal border may be quite 

 straight. The colour may be wholly white, the brown tint 

 may be continued across the middle to the front border, 

 or it may be disposed in radially elongate spots on the ribs. 



Diagnosis. — From C. elegantula by its straighter posterior 

 border, by the prominence of the centre of its lunule, by 

 being more equilateral, and by its colour. 



Type in Dr. Verco's collection. 



Cuna atkinsoni, Tenison- Woods, sp. 



KdJia atkinso7]i, Tenison-Woods, Proc. Roy. Soc, Tasm., 

 1877 (1876), p. 158. Type locality. — Long Bay, Tasmania. 



