108 OBSERVATIONS ON NAIADES, 



In ascribing the locality of York river, Virginia, to the U. obesus, 

 I have reason to believe there is an error. It was so labelled in the 

 collection of the Lyceum of Natural History of New York ; but this, 

 Major Le Conte assures me, must have been done by some transfer or 

 accidental change of the labels; as he procured them in Georgia, 

 from whence he recently obtained a new supply of undoubtedly the 

 same species, and those marked as from York river cannot be traced to 

 that locality. The locality was a matter of surprize to me when I re- 

 ceived them as coming from that river. 



Unio Olivarius. Plate XVI. fig. 38. 



Testa ovatd, transversa, inflatd, pellucidd; valvulis pertenuibus; natibus promi- 

 nulis; epidermide pertenui, ItBvi et oliva colorem habente; dentibus cardinalibus 

 magnis laminatis erectisque, lateralibus laminatis brevibusque; margaritd pertenui 

 albdque. 



Shell ovate, transverse, inflated, pellucid; valves very thin; beaks slightly elevated; 

 epidermis olive, very thin and smooth. Cardinal teeth large, erect and lamelli- 

 form; lateral teeth short and lamelliform; nacre very thin, white and pearly. 



Hab. Burrill river, India, Dr Burrough. 



My Cabinet. 

 Cabinet of Dr Burrough. 

 Cabinet of the Academy of Natural Sciences. 

 Cabinet of Dr Morton. 

 Diam. -7, Length -8, Breadth 1*5 inches. 



Shell ovate, transverse, inequilateral, inflated, pellucid : substance of 

 the shell very thin ; beaks slightly elevated, rounded and devoid of un- 

 dulations: ligament very small: epidermis olive, very thin and smooth: 

 rays obscure, cardinal teeth large, erect and lamelliform ; lateral teeth 

 short and lamelliform : anterior cicatrices slightly confluent : posterior 

 cicatrices confluent : dorsal cicatrices not perceptible ; cavity of the 

 beaks wide : nacre verv thin and bluish white. 



