REPORT ON THE LAMELLIBRANCIIIATA. 243 



This species is considerably swollen, almost exactly equilateral, scarcely gaping at 

 either end, elongate, nearly twice as long as high, sharply rounded at the anterior end, 

 broader behind and shortly rostrate above, with a distinct but not veiy deep sinus just 

 l^eneath, which marks the termination of a slight depression extending from the uml^ones. 

 It is ornamented at intervals with very strong raised ridges, marking periods of growth, 

 so that the surface might be described as ridged and sulcated. The epidermis is thickish, 

 of a dark olive tint upon the lirse, paler and yellower between them. The dorsal margin 

 is only very little sloping on both sides, quite rectilinear behind, and very slightly 

 excurved in front. The umbones are small, central, and but very little raised above 

 the dorsal line. The hinge-plate is not remarkably strong, and in the largest specimen 

 bears seventeen sharp close-set teeth on each side the ligament-pit, which is deep and a 

 little prominent within the valves. The interior is glossy, somewhat iridescent, whitish, 

 zoned with a bluish tint, and stained at times with a pale reddish or yellowish colour. 

 The pallial sinus is short, narrow, and rather acute. 



Length 24 mm., height 13, diameter 12. 



Habitat. — Balfour Bay, in 20 to 60 fathoms ; Betsy Cove, in 15 to 25 fathoms ; 

 Howe's Foreland, in 95 fathoms; and Station 149g, in 110 fathoms; all oft" Kerguelen 

 Island. 



This species cannot be conveniently compared with any at present known. Tlic 

 specimens described by Professor Martens were rather smaller than the largest ohrained 

 by the Challenger. 



Yoldia suhcequilateralis, Smith. 



Toldia sitbcpqmlaterah's, Smith, 

 Yoldia suhxquilaferalis, Smith, 



Habitat. — Station 149d, Eoyal Sound, Kerguelen Island, in 28 fathoms ; volcanic 



Toldia sitbcpquilateralis, Smith, Ann. and Mag. Nat. Hist., 1875, vol. xvi. p. 73. 

 Yoldia suhcequilateralis, Smith, Phil. Trans. Roy. Soc, 1879, vol. clxviii. p. 187. 



mud. 



Besides the internal cartilage, the valves are connected above by a slight external 

 ligament or thickening of the epidermis on each side of the umbones, which are generall}- 

 eroded. The species is characterised by its compressed form, its gaping ends, and few 

 teeth. The interior is bluish-white, zoned with a darker tint. 



Sarepta, A. Adams. 



Sarepta ahyssicola, n. sp. (PI. XX. figs. 6—66). 



Testa tenuis, parva, insequilateralis, antice angusta, acute rotunda ta, postice latior, 

 nitens, alba, aliquanto iridescens, incrementi Lineis tenuissimis sculpta. Margo dorsi 

 anticus brevis, paulo excurvatus et declivis, posticus parum arcuatus, minus obliquus. 

 Ventris margo late curvatus, antice oblique ascendens, postice subito sui'sum arcuatus. 



