OF CONCHOLOGY 205 



DESCRIPTIONS OF TWO NEW SPECIES OF 

 MONOCONDYLCEA. 



BY JOHN G. ANTHONY. 



MoNocoNDYLCEA Peguensis, AntTiony. — t. 18, f. S. -C 



Description. — Shell smooth, rhombic-ovate, inequilateral, 

 somewhat inflated, sub-biangular behind; substance of the 

 shell thick; beaks rather prominent, eroded, but apparently 

 not undulated; ligament short and thin; epidermis dark brown 

 or nearly black, smooth over the umbones and on the anterior 

 portion of the shell, but having the sub-truncate posterior 

 portion nearly covered with distinct corrugated folds, more 

 prominent near the hinge margin; cardinal teeth prominent, 

 curved and slightly bilobed, particularly in the right valve* 

 anterior cicatrices distinct and deeply impressed; posterior 

 cicatrices confluent; dorsal cicatrices deeply impressed, placed 

 in a curved line under the beaks ; nacre light salmon color 

 and very iridescent. 



Dimensions. — Length 3-7 inches, breadth 24 inches, diam. 

 1-2 inches. 



Habitat. — Pegu. 



Museum Comp. Zoology, Cambridge, Mass. Cabinet of 

 Hugh Cuming, London. Cabinet of Gr. W. Tryon, Jr. 



Observations. — This species, recently received from Peo-u 

 seems to differ essentially from all hitherto described species. 

 It is of a somewhat rhombic form, has very distinct but rather 

 distant lines of growth, which, however, become closer near 

 the basal edge. The beaks are considerably eroded, but show 

 no marks of any undulations there. From M. crehristriata it 

 differs in being larger, more inflated, more elliptical in form, 

 and the epidermis is smoother and darker in color ; the nacre 

 has a rich satiny lustre, which near the edge of the shell be- 

 comes of a highly iridescent hue. Four specimens only of 

 this species were received, but they are very constant in char- 

 acter, and cannot well be mistaken for any other species. 



MONOCONDYLCEA CREBRISTRIATA, Anthony. — t. 18, f 1. 



Description. — Shell rhombic, strongly striate, very inequi- 

 lateral, depressed, bi-angular behind; substance of the shell 



