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



Carditella capensis, n. sp. (PI. XV. figs. 7 -7c). 



Testa parva, sequilateralis, mediocriter eompressa, triaugulariter ovata, albida, irregii- 

 lariter rufo notata, costis radiantibus tenuibus pulcherrime uodidosis circiter 18 

 instructa. Margo dorsi utrinque levissime concavus, ventralis mediocriter arcuatus. 

 Dentes cardinales duo insequales in utraque valva, antico valvse dextrae magno, conico, 

 triangulari. Laterales utrinque distincti, ajquidistantes. Ligamentum parvum, internum, 

 infra umbones locatum. Cicatrices subprofundge, magnse. Margo ventris intus duplex, 

 dentatus. 



This is a fairly solid little species, triangidarly ovate, angular above, curved below, 

 and rather sharply rounded at the sides. It is moderately compressed, about equilateral, 

 white, and irregularly marked upon the nodulose ribs with red. The sculpture consists 

 of about eighteen fine radiating costse, which are covered with closely arranged and rather 

 compressed little nodules. The intervening grooves are rather deep, somewhat narrower 

 than the ridges, and exhibit concentric lines of growth. The dorsal areas on both sides 

 of the beaks are lanceolate, smooth, and a little sunken. The beaks are about central, 

 slightly eroded at the extreme apex, and scarcely incline either towards the anterior or 

 posterior side. The dorsal margins are very slightly concave, about equal in length, 

 and converge at an angle of about 100 degrees. There are two unequal cardinal teeth in 

 each valve, and a latei-al on each side. The front cardinal in the right valve is stout, 

 triangular, and conical, the hinder one being much smaller, slender, and neither joined to 

 it, nor Teaching to the dorsal edge above. The cardinals in the left valve are very 

 divergent and more equal, the posterior one, on the contrary, being rather larger than 

 the other. The anterior lateral in the right valve, and the posterior in the left, are 

 separated from the outer edge by a distinct groove, which receives the marginal lateral 

 respectively of the opposite valve. The ligament is small, entirely internal, and placed 

 in a little pit beneath the apices. The muscular scars are rather large and deejD, the 

 anterior being longer than the posterior, which is roundish. The simple pallial line is 

 also distinct and rather far from the margin, which is strongly dentate, and of a double 

 contour, and the hinge-line between the umbones and the lateral teeth, under the 

 microscope, is seen to be very peculiarly corrugated. 



Length 4 mm., height 3^, diameter 2|-. 



Habitat. — Simon's Bay, Cape of Good Hope, in 15 to 20 fathoms. 



This species is very like Carditella pallida, Smith, the type of the genus, from Port 

 Piosario, Patagonia. It differs in being a little more solid, has a somewhat stronger hinge, 

 more slendec, more numerous, and more distinctly noduled ribs. 



