Illustrations of Littlt Known Unionidu . 



*57 



ILLUSTRATIONS OF LITTLE KNOWN UNIONIDU. 



By R. Ellsworth Call. 



I. Unio /esopls, Green.* 

 Plate VI. 



In 1827 Dr. Jacob Green obtained from " the rivers in the neigh- 

 borhood of Pittsburg " an undescribed Unio to which he gave, with 

 formal description, in Contributions of the Maclurian Lyceum to the 

 Arts and Sciences, I., p. 45, July, the name Unio cesopus. Later in- 

 vestigations developed the wide distribution in the rivers of the west 

 of this shell ; but its original description is so rarely seen that nearly 

 all modern identifications are traditionary. Frequently this highly 

 characteristic shell is received from collectors under the various names 

 of Unio rubiginosus Lea, Unio coccineus Lea, and occasionally with 

 specimens of Unio ellipsis Lea. The plate which Dr. Green designed 

 to illustrate this species is a rather poor specimen of early lithograph- 

 ing and does not well exhibit its characters ; the male shell was 

 employed. 



* Jacob Green, M. D., was born in Philadelphia on the 26th of July, 1790 ; 

 he died in that city on February 1st, 1841. He was well and favorably known 

 as an educator and was for a number of years professor of chemistry in the Jef- 

 ferson Medical College. His scientific work was not extensive but was of a most 

 excellent character. He was a distinguished student of mollusca and of trilo- 

 bites. He was the discoverer of that small but most interesting form from the 

 Utica Shale known as Triarthrus beckii. 



