﻿EXOTIC UNIONID.E. 257 



Shell closely and delicately silicate, transversely elliptical, somewhat inflated, very 

 inequilateral ; valves thin ; beaks rather prominent, smooth at the tip ; epidermis 

 olive-green, shining, obscurely rayed ; cardinal teeth small, lamellar and oblique ; 

 lateral teeth long, acicular and nearly straight ; nacre bluish white and iridescent. 

 Unio Wilsonii, Lea. Proc. Acad. Nat. Sci., 1859, p. 153. 



Hab. — Eastern Branch of Isaac's Plain, New South Wales. T. B. Wilson, M. D. 



Cabinet of the Academy of Natural Sciences. 

 Diam. -6, Length 1, Breadth 1-9 inch. 



Shell closely and delicately sulcate, transversely elliptical, somewhat inflated, very 

 inequilateral ; valves thin ; beaks rather prominent, pointed at the tip and free from 

 any undulations ; ligament short, very thin and light brown ; epidermis olive green, 

 shining, obscurely rayed, and with distant marks of growth ; umbonial slope slightly 

 raised and rounded ; cardinal teeth small, lamellar, oblique, double in the right and 

 single in the left vale ; lateral teeth long, acicular and nearly straight ; anterior 

 cicatrices confluent and scarcely perceptible ; posterior cicatrices confluent and scarcely 

 perceptible ; dorsal cicatrices placed in the centre of the cavity of the beaks ; cavity 

 of the shell rather deep and rounded ; cavity of the beaks shallow and subangular ; 

 nacre bluish white and iridescent. 



Remarks. — Only a single specimen of this species was received by Dr. Wilson. It 

 is a very simple species, with no marked character but that of the cardinal tooth 

 being double in the right valve, which is not very uncommon in the Asiatic species, 

 when the teeth are lamellar. In outline it closely resembles U. inornatus, (nobis), 

 from Siam. It is a little more transverse, and the epidermis is darker, being more olive 

 than yellow. I name it after Dr. Wilson, who kindly submitted it to my exami- 

 nation. 



Unio Mauritianus. PI. 40, fig. 138. 



Testa laevi, elliptica, compress^, ingequilaterali ; valvulis pertenuibus ; riatibus prominulis ; epiderraide 

 olivo-luteS., nitida, obsolete radiata ; dentibus cardinalibus minimis, compressis, obliquis ; latcralibus 

 longis, acicularis subeurvisque ; margarita alba et paulisper iridescente. 



Shell smooth, elliptical, compressed, inequilateral ; valves very thin ; beaks slightly 

 prominent; epidermis olive yellow, shining, obscurely radiate; cardinal teeth very 

 small, compressed and oblique ; lateral teeth long, acicular and somewhat curved ; 

 nacre white and slightly iridescent. 



Unio Mauritianus, Lea. Proc. Acad. Nat. Sci., 1859, p. 152. 



Hab. — Island of Mauritius. H. Cuming. 



Cabinet of Mr. Cuming. 

 Diam. *5, Length -8, Breadth 1-3 inch. 



Shell smooth, elliptical, compressed, inequilateral ; substance of the shell very thin, 

 semitranslucent ; beaks slightly prominent ; ligament very long and thin ; epidermis 



