Mollusca from the Arabian Sea. 265 
sculpture. In general form it recalls some examples of the 
West-Indian Hipponyx antiquatus (L.). ‘The apex is so 
much recurved as to pass*the posterior margin of the aperture. 
Crassatella indica. 
Testa valde ineequilateralis, crassiuscula, antice rotundata, postice 
subquadrata, costis concentricis crassiusculis numerosis utrinque 
attenuatis instructa, albida, epidermide haud nitida, lutescente 
induta; margo dorsi anticus valde descendens, concayus, posticus 
longior, minus obliquus, rectus; umbones prominentes, longe 
antemediani, incurvati, vix contigui, acuti; lunula cordata pro- 
funde excavata, lineis incrementi tenuibus striata; area dorsi 
postica excavata, lanceolata; pagina interna alba vel ceruleo- 
alba ; cicatrices parvee, subprofund, subequales ; margo valva- 
rum inferior intus tenuiter denticulatus ; cardo normalis, dentibus 
principalibus striatis. 
Longit. 28 millim., alt. 24, diam. 172. 
Hab. Lat. 21° 30’ 15” N., long. 68° 05’ 45" E., Arabian 
Sea, off Gujerat, 82 fathoms. 
Distinguished from allied species by difference of form and 
costulation. ‘The ribs near the posterior extremity are more 
or less obsolete or concealed by the periostracum. 
Amussium andamanicum, Smith. 
Amussium andamanicum, Smith, Ann. & Mag. Nat. Hist. 1894, 
vol. xiv. p. 172, pl. v. figs. 18, 14. 
Hab. Lat. 15° 11' N., long. 72° 28' 45” E., Arabian Sea, 
west of Goa, in 931 fathoms. 
Two specimens from this locality are rather larger than the 
type from the Andaman Sea, being 43 millim. in length and 
51 high. The greater development of the concentric lamelle 
towards the lower margin of the left valve, as shown in the 
figure, appears to be characteristic of the species; also the 
feebleness of the central radiating lire within the valves is 
maintained. The microscopic structure of the valves is 
different. The right valve is minutely punctate everywhere, 
and the fine concentric ridges towards the umbo are crossed 
by very short minute striez. The left valve, on the con- 
trary, may be described as smooth. The conspicuous differ- 
ence in the structure of the valves is best seen by means of 
transmitted light. 
