MACTRA.— Plate XIV. 



inequilateral, gaping at each end, dirty-white, sub- 

 eroded, covered towards the margin with a brown 

 epidermis, transversely irregularly closely striated, 

 anterior side short and rounded, posterior twice 

 as long, slightly flexuously angled; umboes very 

 small, approximated; lunule and area indistinct; 

 sinus of the mantle large, obtuse, dilated at the base. 



Deshayes, Pro. Zool. Soc. 1854. 



Hub. Moreton Bay, Australia. 



A very compressed suborbicular shell, rough and eroded, 

 except where covered with a dark olive-brown fibrous epi- 

 dermis. 



Species 70. (Mus. Cuming.) 



Mactra explanata. Blact. testa ovato-subtrigond, com- 

 pressd, eburned, Imvigatd, nitente, latere antico lata, 

 obtuso, paulo breviore, postico declivi, atteniiato. Id- 

 ante ; timbonibus parvis, approximatis ; lunuld lanceo- 

 latd, medio elevatd, area angustd, concavd, anguld bi- 

 carinatd utrinque notatd ; cardine peculiariter lato et 

 excavato ; sinu pallii lato, profundiusculo, obtitsissimo. 



The smooth Mactra. Shell ovately subtriangular, 

 compressed, ivory-white, smooth, shining, anterior 

 side broad, obtuse, rather the shorter, posterior 

 slanting and attenuated, gaping; umboes small, ap- 

 proximated ; lunule lanceolate, raised in the middle, 

 area narrow, concave, with a two-keeled angle on 

 each side ; hinge peculiarly broad and excavated ; 

 sinus of the mantle broad, rather deep, very obtuse. 



Deshayes, Pro. Zool. Soc. 1854. 

 Hab. Swan Eiver, Australia. 



A subpellucid shining ivory-white compressed shell, with 

 a very peculiar hinge, the lateral teeth in each valve forming 

 an unusually broad lamellar trench. 



Species 71. (Mus. Cuming.) 



Mactra egena. Moot, testd ovato-transversd, compressd, 

 huBquUaterali, candidimmd, transversim irregulariter 

 striata, latere antico brevi, angustato, super/ie declivi, 

 latere postico latiore ; area angustissimd, profunda, 

 utrinque angulum irregulariter plicato-notatd, lunuld 

 lanceolatd ; timbonibus parvis, approximatis ; sinu 

 pallii profunda, lalo, digitiformi, dimidiam partem 

 valvarum attingente. 



The distressed Mactra. Shell ovately transverse, 

 compressed, inequilateral, very white, transversely 

 irregularly striated, anterior side short, narrowed, 

 slanting at the upper part, posterior side broader : 

 area very narrow, deej), with an irregularly plaited 

 obtuse angle on each side, lunule lanceolate ; umboes 

 small, approximated ; sinus of the mantle deep, broad, 

 finger-shaped, reaching to the half of the valve. 



Deshayes, Pro. Zool. Soc. 1854. 



Hab. ? 



Somewhat resembling ilf. Dysoni, but more inequilateral, 

 and roughly plicated on each side the cardinal area, which 

 is pressed inwards. 



J 



