M0LLTJS0A. 101 



umbo. In the left valve; the single Lateral tooth on each side is 

 elongate, narrow, and erect. Only one cardinal tooth (unless the 

 front raised edgo of the ligamental fossa be considered a tooth), which 

 is elongate, but little raised, situated between the pit and edge of 

 the lunule. Muscular scars pyriform, the front one elongate, the 

 posterior more rounded. Pallial sinus extending halfway across the 

 valves, sharply rounded at the end. A second sinuation within 

 tho other, and consequently shorter and less acutely curved, is a 

 remarkable feature in both valves of the single perfect shell before 

 me; in a separate valve this is not noticeable, but may have been 

 obliterated, as the specimen is somewhat sea-worn. The inner sur- 

 face of this species is glossy and radiately suhstriated, one impressed 

 ray from the umbones to the end of the mantle-sinus being especially 

 conspicuous. Length .'>')] millim., height 24, diameter 12. 

 Hah. Thursday Lsland, Torres Straits, 4-6 fms. ' 

 This very interesting species bears a rather close relationship 

 to Mactra triangularis of Lamarck; it is, however, quite distinct. 

 It is a trifle shorter, less angular, not so strongly concentrically 

 costate, has au excavated lunule and a sunken area not defined 

 by carinate edges, and the dorsal margins not prominent, forming a 

 keel on each side ; the umbones as in M. triangularis. M. aspersa, 

 Sowerbv. is a more finely sculptured shell, more rounded posteriorly, 

 with a shallower lunule and a narrower dorsal area. The pallial 

 sinus in the present species reaches halfway across the valve, whilst 

 in M. aspersa it has a further extension and lacks the duplex feature 

 described 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 two 

 minor ridges. In the Cumingian collection there is a second 

 specimen, somewhat larger than that figured by Reeve, having a 

 length of 32 millim. and a width of 47. 



'&■ 



31. Cardium reevianiun. 



Bunker, Kovitates Conch, p. 22, pi. 6. figs. 6, 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, h ; Rb'mer, Conch.-Cah. p. 112. 



Hah. Corrigidor, Philippines (Cuming) ; Flinders and Clairmont 

 Islands, N.E. Australia (Coppinger). 



