FRESHWATER AND LAND SHELLS. 39 



Unio medellinus. Plate XII. fig. 34. 



Testa elUpticd, transversa, subcompressd, inotquilaterali ; valvulis subtenuibus ; natibus sub- 

 prominulis ; epidermide luleola, radiata ; denlibus cardinalibus parvis ; lateralibus longis sub- 

 curvisque; margarita alba et iridescente. 



Shell elliptical, transverse, rather compressed, inequilateral ; valves somewhat thin ; 

 beaks rather prominent ; epidermis yellow^ish, radiated ; cardinal teeth small ; lateral 

 teeth long and somewhat curved ; nacre white and iridescent. 



Hab. River Medellin, near Vera Cruz. Dr Burrough. 



My Cabinet. 

 Cabinet of Dr Burrough. 

 Diam. -7, Length 1-3, Breadth 2-3 inches. 



Shell elliptical, transverse ; rather compressed, subemarginate at base, 

 inequilateral ; substance of the shell rather thin ; beaks rather promi- 

 nent; ligament rather long and slender; epidermis yellowish, w^ith 

 numerous green rays over the whole disk ; anterior cicatrices distinct ; 

 posterior cicatrices confluent; dorsal cicatrices placed in the centre of 

 the cavity of the beaks; cavity of the shell shallow; cavity of the 

 beaks very shallow; nacre white and iridescent. 



Remarks. — This species was among those sent by Dr Burrough from 

 Vera Cruz. One of the two specimens received is apparently only 

 half grown. The very strong resemblance these specimens bear to 

 U. radiatus (Gmelin), has caused rae to hesitate in considering 

 the species distinct. The younger individual is more transverse than 

 any specimen of radiatus I have seen, and the emargination is a cha- 

 racter which that shell does not possess. 



