EEPORT ON THE LAMELL1J5RANCHTATA. 227 



Nucida torresi, n. sp. (PI. XVIIl. figs. 9-9a). 



Testa parva, solidiuscula, triangularis, paulo inajquilateralis. convexa, albido-fnsccsccns, 

 epiderinide 1 induta, eostulis tenuibus concentricis iustructa, radiatimque striata. 



Lunula magna, in medio prominens, impressione baud profunda circumscri])ta. ]\Iargo 

 dorsi utrinque vix excurvus ; posticus paulo magis elongatus, sed minus obliquus. 

 Pagina interna albo-margaritacea, margine inferiore intus minute crenulato. Denies ad 

 quatuordecim fortiusculi, props medium seriei fossa parva ligamenti intcrrupti. 



This is rather solid for so small a species, a little unequal-sided (tlio anterior end 

 being the shorter), of a triangular form, bluntly angled at the anterior end, ;ind rather 

 more rounded behind. It is considerably convex, of a whitish brown colour, and, in a 

 dead condition (the few valves preserved are in this state), presents no trace of an 

 epidermis. The sculpture consists of numerous concentric riblets, which are attenuated 

 at the sides, and exhibit, principally in the intervening grooves, fine radiating striic. 

 The dorsal margins converge almost to a right angle, and are scarcelj^ at all excurved, 

 the anterior being shorter and more oblique than the posterior, and faintly bulged bj" 

 the central line of the large lunule, which is marked off by a shallow depression. The 

 umbones are rather blunt, but incurved at the small tip and decidedly in front of the 

 centre. The interior is thickened, pearly white, and minutely crenulated along the 

 lower border. The hinge-plate is strong, and sup)ports about fourteen teeth, of which 

 six are usually in front of the small non-projecting ligamental pit. 



Length 2fmm., height 2|, diameter 2. 



Habitat. — Station 185, east of Cape York, North Australia, in 135 f\ithoms ; coral sand. 



This species is remarkable for its solidity, its comparative e(pial-sidedness, and the 

 strong character of the concentric sculpture. 



Nvcula 2^ernamhi(censis, n. sp. (PI. XVIII. figs 10-10«). 



Testa irregulariter quadrate ovata, modice convexa, insequilateralis, eoncentrice 

 tenuiter sulcata et lirata, alba, nitida. Umbones antemediani, paulo supra marginem 

 dorsalem producti. Linea cardinis mediocriter fortis, dentibus ad decem in.structa. 



This species is longer than high, irregularly squarely ovate, moderately convex, 

 somewhat inequilateral, white, glossy, and sculptured with regular, fine, concentric 

 grooves, and intervening lir^e, except upon and towards the smooth apices. The lunule 

 and dorsal area are not defined. The posterior dorsal margin rises higher, and is longer, 

 than the anterior, which, however, is more sloping. The ventral outline is widely 

 arcuate, and forms with the hinder lateral margin a rather more sharply rounded 

 extremity than in front. The beaks, viewed from the side, are somewhat obtuse, 



