Report on the zoological collections made in the Indo-Pacific Ocean ...

lessMOLLtrSCA. 101umbo. In the left valve, the single lateral tooth on each side iselongate, narrow, and erect. Only one cardinal tooth (unless thefront raised edge of the ligamental fossa be considered a tooth), whichis elongate, but little raised, situated between the pit and edge ofthe lunule. Muscular scars pj'riform, the front one elongate, theposterior more rounded. Pallial sinus extending halfway across thevalves, sharply rounded at the end. A second sinuation withinthe other, and consequently shorter and less acutely curved, is aremarkable feature in both valves of the single perfect shell beforeme ; in a separate valve this is not noticeable, but may have beenobliterated, as the specimen is somewhat sea-worn. The inner surfaceof this species is glossy and radiately substriated, one impres«'edray from the umbones to the end of the mantle-siniis being especiallyconspicuous. Length 36| millim., height 24, diameter 12,Hah. Thursday Island, Torres Straits, 4-6 fms.This very interesting species bears a rather close relationshipto Mactra trianr/idans of Lamarck ; it is, however, quite distinct.It is a trifle shorter, .angular, not so strongly concentricallycostato, has an excavated lunule and a simken area not definedby carinate edges, and the dorsal margins not prominent, forming akeel on each side ; the umbones as in M. trianr/uJaris. M. aspersa,Sowerby, is a more finely sculptured shell, more rounded posteriorly,with a shallower lunule and a narrower dorsal area. The pallialsinus in the present species reaches halfway across the valve, whilstin M. aspersa it has a further extension and lacks the duplex featuredescribed previously,30. Mactrinula angulifera.Mactra angulifera, Deshayes, Proc. Zool. Soc. 1854, p. 70; Reeve,Conch. Icon. fig. 83.Hah. Island of Ticao, Philippine Islands {Cuming); Port Curtis( Coppinger).Behind the conspicuous keel which marks off the posterior area,about midway between it and the margin, there are one or twominor ridges. In the Cumingian collection there is a secondspecimen, somewhat larger than that figured by Reeve, having alength of 32 millim. and a width of 47.31. Cardium reevianum.Dunker, Novitates Conch, p. 2"2, pi. 6. figs. Q, 7, 8.Hah. Port Darwin, 8-12 fms., bottom mud and sand (Coppinger) ;Port Essington (Mus. Cuming).Cardium vertehratum, Jonas (Zeitschr. fiir Malak. 1844, p. 33),from West Australia, is apparently closely related to the present species.32, Cardium hystrix.Reeve, Conch. Icon. figs. 40 a, b ;Romer, Conch.-Cab. p, 112.Hah. Corrigidor, Philippines {Cuming) ; Flinders and ClairmontIslands, N,E. Australia {Coppinger).