HO. 1139. itKKP-WATKli MOLLUSCAVERRILL AND BUSH. 81!) 



rounded with the dorsal margin rapidly sloped ; ventral margin broadly 

 and evenly rounded; posterior end somewhat obliquely truncated with- 

 out any definite boundary, but with a distinct depression extending from 

 under the beak to about the middle of the posterior margin ; postero- 

 dorsal margin nearly straight, longer, and sloping less rapidly than the 

 anterior. The entire surface is covered with minute, irregular, raised, 

 granules and pretty distinct, but irregular, lines of growth and slightly 

 raised, distant, thin, radiating lines running from the umbo to the 

 margin, except on the posterior end where the lines of growth become 

 more prominent; these radial lines are however, in many places, rather 

 faint and seem to consist mainly of the thin, brownish epidermis, which 

 is lacking in certain parts. Minute grains of sand and shells of Foram- 

 iuifera are firmly adherent to the surface, mainly along the radial 

 lines, and especially posteriorly. The interior is white, lustrous and 

 but slightly nacreous. Muscular and pallial scars indistinct. The 

 hinge-margin is thin ; in the left valve the anterior border is somewhat 

 thickened in the luuular area and terminates abruptly in a rounded, 

 tooth-like shoulder just under the beak; the posterior margin shows a 

 slightly raised elongated, roughened area for the attachment of the 

 resilium, commencing under the beak and running back for some dis- 

 tance within the margin, on its nearly vertical inner surface, so that it 

 is scarcely visible in a front view. Ossicle not observed. Ligament 

 very thin, occupying a groove along the posterior margin. 



Length, ID mm.; height, 13 mm.; breadth, 9 mm.; from the beak to 

 the antero-dorsal angle, 7 mm. ; to the postero-dorsal angle, 12 mm. 



One valve (No. 525(51), station 2402, N. lat. 45 22', W. long. 58 

 43' 45", in 75 fathoms, 1885. 



This species is allied to L. urenosa (Moller) with which it agrees very 

 closely in the character of the external surface and structure of the 

 hinge. It differs in its longer, more ovate form, in its more produced 

 anterior end, and in its less swollen umbo. 



Family P 



CLIDIOPHORA INORNATA, new species. 

 (Plate XCV, figs. 5, 6.) 



Shell small, much compressed, very inequilateral, posterior end nar- 

 rowed, somewhat accumulate, the right valve flat or slightly convex 

 and the left valve a little swollen. Limbos not prominent; beaks small 

 and appressed. The antero-dorsal margin is slightly convex and 

 slopes rapidly to the bluntly rounded anterior end; the ventral margin 

 is broadly rounded and slightly prominent, considerably behind the 

 middle, beyond which it is incurved to meet the posterior rostral 

 angulation; the posterior end is produced into a short, narrow, sub- 

 truncated, slightly upturned rostrum, its lower angle formed by a some 

 what prominent, radial rib or ridge, extending from the beak (on the 



