REPORT ON THE LAMELLIBRANCHIATA. 55 



tliininsh, equilateral, morlevately convex, white, and ornamented with innumerable minute 

 elevated granules arranged in (|uincuncial foshiou. The dorsal margin is considerablj' 

 ol)li(|ue on both sides of the ])rominent beak which is well curved over towards the 

 iVoiit, and sniDOtli and glossy at the tip, in front of wliicli there is a lunular depression, 

 which is not, however, defined by a line. The anterior dorsal slope is a trifle concave, 

 the posterior side, on the contrary, l)eing slightly convex, exhibiting a sharpish keel or 

 ridge very close to the edge, marking oft" a linear dorsal area. The single cardinal 

 tooth is large, strong, erect, and situated immediately beneath the apex of the umbo. 

 The interior of the valve is whitish and somewhat pearl)^. 



Length 4|- mm., height 4^, diameter of valve 1|^. 



Habitat. — Station 185b, east <jf Cape York, North Australia, in 155 fathoms ; coral 

 sand. 



This is a shorter shell than the European Povomija granidata of Nyst, with more 

 sloping dorsal margins and a more c-urved ventral outline. It is also more coarsely 

 granulated, and the pit containing the internal ligament is smaller and more equUater- 

 ally triangular. 



Povoiiiija Iwvis, n. sp. (I'l. XI. tigs. 3—36). 



Testa insequilateralis, ovata, antice pauIo acuminata, postice latior, leviter sub- 

 truncata, alba, tenuis, nitida, incrementi lineis levibus striata, undicj^ue microscopice 

 subpunctata. JMargo dorsi utrinque declivis, postice subrectUinearis, antice leviter 

 excurvatus, prope umbonem contractus, lunulam parvam concavam formans. Margo 

 ventris late arcuatus. Umbones parvi-, paulo supra marginem dorsalem producti, 

 alic|uanto post medium siti. ^"idva. dextra dente unico subvaUdo infra umbonem 

 instructa, lineaque cardinis anti(;e profunde sulcata. Proxime sub margine dorsali pone 

 umbonem est liganienti sulcus parvus hand })rofundus. Pagina interna nitida, sul)- 

 margaritacea, ladiatim substriata. 



Of this species only tluee right valves are at present known. It is of an ovate 

 form, a little acuminate in front, broader and somewhat truncated behind. It is not 

 very convex, rather inecj^uilateral, the anterior side being the longer. It is thinnish, 

 white, glossy, sculptured with very fine lines of growth, and everyA\'here exhibits a micro- 

 scopic shagreened surface, only \asible under a compound lens. The front dorsal margin 

 is a little curved and sloping, the posterior being shorter, straighter, and more oblic[ue, 

 and turned at right angles to the rest of the valve, forming a narrow dorsal area. 

 The ventral outline is regularly and widely arcuate, ascending equally at both ends. 

 The l>eaks are small, slightly raised aljove the hinge-line, are situated behind the centre, 

 and curve towards the front over a small concave lunule. The interior is glossy, 

 semipearly, and finely radiately substriated, especially towards the lower margin. There 



