218 THE VOYAGE OF H.M.S. CHALLENGER. 



circa 21 instructa; lunula cordata, rufescens, impressa. Pagiua iutcnia all)a, umbones 

 versus sordide fuscesceiis. Dens unicus cardinalis in valva dextra crassus, triangularis, inter 

 duos valvae siuistrse interpositus. Dentes laterales in utraque valva parvi, parum remoti. 



This species is somewhat squai^e, narrowed and rounded in front, broad and 

 curvedly truncate behind. It is very inecpilateral, moderately convex, white and pro- 

 miscuously spotted with red upon the radiating costse which adorn the surface. These are 

 rather fine, about twenty-one in number, finely nodulose, and about equal in width to 

 the grooves between them, five or six on the upper part of the posterior end being a 

 trifle finer than the rest. The posterior dorsal margin is almost horizontal and straight, 

 the anterior, on the contrary, being very suddenly oblique and the ventral margin is 

 broadly curved. The lunule is small, cordate, reddish, a little sunken, and clearly 

 defined. The hinge consists of a strong central triangular tooth in the right valve which 

 fits in between two in the left. There is a distinct lateral tooth on each side in both 

 valves, which are about equidistant, but not very remote from the cardinals. The 

 interior is white, but stained with brown beneatli tlie umbones, and of course dentate at 

 the margin. 



Length 6f mm., height 5, diameter 3f. 



Habitat. — Station 163b, Port Jackson, New South Wales, in 35 fathoms; hard ground. 



The ligament in this species, as well as in CarditeUa torresi, does not quite 

 correspond with that of the t}q)e of the genus, no portion of it apparently l)eing internal 

 beneath the umbones. 



CarditeUa infans, n. sp. (PI. XV. figs. 10-lOa). 



Testa minuta, solidiuscula, rotundata, convexa, luuulata, albida, costis circa 18 rotun- 

 datis, confertis, pulcherrime granulatis instructa. Lunula cordata, Isevis, in medio pro- 

 /ninens. Umbones paulo antemediani, incurvati, antrorsus versi. Margo dorsi posticus 

 decHvis, parum arcuatus, anticus subexcavatus ; margo ventris valde curvatus. 



This species, though so small, apparently is adult. It is rounded with the exception 

 of the somewliat prominent beaks, a little inequilateral, whitish, fairly solid and convex, 

 and exhibits a smooth cordate lunule, which is rather prominent along the middle and 

 thus interrupts the otherwise concave front dorsal oblique slo^ie. The sculpture consists 

 of about eighteen rounded radiating ribs which are twice or three times as broad as the 

 narrow deep grooves between them, and are covered with closely packed transverse 

 tubercles. The umbones are peaked, somewliat in advance of the middle, well incurved, 

 and inclined over towards the front. There is a single central stronsr acute triangular 

 cardinal tooth in the right valve which fits in between two divergent but smaller teeth in 



