118 THE VOYAGE OF H.M.S. CHALLENGEE. 



scarcely consider the two to belong to the same species ; but it is not uncommon amongst 

 Ostracoda- to find shells strongly sculptured in the earlier stages of life becoming 

 encrusted with a limy deposit, and thus losing their original surface-markings in old 

 age. A process of this kind I suppose to have taken place in the specimens figured 

 at a-d. At any rate, it would be unreasonable to refer to distinct species shells 

 occurring together in one dredging only, and at the same time so much alike in general 

 character. 



[PI. XXVIII. fig. 6, a-f. a Carapace of male seen from left side, h from above, 

 c from below, c? from front; e female seen from left side, /from above. Magnified 50 

 diameters.] 



4. Loxoconcha africana, n. sp. (PI. XXVIII. fig. 3, a-d). 



Carapace, seen from the side, flexuous, subovate, highest about the middle, slightly 

 depressed in front, height equal to at least two-thirds of the length ; anterior extremity 

 well and evenly rounded, posterior scarcely broader than the anterior, rounded, gently 

 emarginate at the upper angle, not produced ; dorsal margin evenly and moderately 

 arched, ventral sinuated in front, convex behind ; seen from above, ovate, acuminate in 

 front, rounded ofi" and mucronate behind, greatest width in the middle, and equal to 

 more than half the length ; end view broadly ovate, rounded both at base and apex, 

 dorsal very nearly as wide as the ventral margin, height not very much greater than the 

 width. Surface of the shell smooth, partially marked with small circular punctures, and 

 with a few scattered circular papillae. Length, l-42d of an inch ("6 mm.). 



Dredged off St Vincent, Cape Verde, in 1070 to 1150 fathoms, muddy bottom. 



[PI. XXVIII. fig. 3, a-d. a Carapace seen from left side, h from above, c from below, 

 d from front. Magnified 50 diameters.] 



5. Loxoconcha pumicosa, n. sp. (PI. XXVIII. fig. 2, a-d). 



Carapace short, tumid ; seen from the side, subrhomboidal, greatest height situated 

 in the middle, and equal to two-thirds of the length ; extremities about equal in height, 

 anterior rounded, posterior oblique, produced above the middle into a short, truncated 

 beak, dorsal margin moderately arched, and slightly sinuated behind the middle, ventral 

 gently convex ; seen from above, the outline is lozenge-shaped, very wide in the middle, 

 and tapering equally to the extremities which are subacute, width about equal to the 

 height ; end view broadly heart-shaped, wide, and nearly fiat below, rounded, and but 

 slightly tapered above. The surface of the shell is sculptured with rather closely- and 

 concentrically-set subrotund excavations of moderate size, which on the ventral surface 

 are arranged in longitudinal furrows. Length, l-48th of an inch ("52 mm.). 



Dredged off Booby Island, lat. 10° 36' S., long. 141° 55' E., 6 to 8 fathoms (Station 

 187) ; and at Nares' Harbour, Admiralty Islands, 16 fathoms. 



