ÜNIO MISOOLENSIS. 



259 



NOTE XXXVI. 

 DESCRIPTION OF A NEW SPECIES OE UNIO 



BT 



M. M. SCHEPMAN. 



Unio misoolensis ^ d. sp. 



Shell elongated , rather compressed , very inaequilateral , 

 the umbones laying at about one sixth of the whole length 

 of the shell , rather smooth , with numerous fine concentric 

 striae; umbones little prominent, decorticated in the adult, 



in half grown shells with conspicuous radiating folds , 

 extending more or less over the disk of the shell; moreover 

 a few radiating grooves occupy the anterior part of the 

 shell , and microscopic radiating wrinkles of the epidermis 

 cover. the posterior slope; epidermis reddish-brown in the 

 adult, yellowish olive-green in the young ones. Upper 

 margin slightly curved , anterior margin rounded , slightly 

 protruded below ; ventral margin incurved , posterior margin 

 forming with the upper one a more or less obtuse angle , 



Notes from the Leyden Museum, Vol. XVIII. 



