^^I'soi!^'] PROCEEDINGS OF THE NATIONAL MUSEUM. 105 



Museum (N"o. 85895) also contains specimens from the Kio Salado, Kew 

 Mexico, collected by Lieutenant Beale. It varies in color externally 

 from blackisb brown to olivaceous green, with hints of radiating mark- 

 ings of lighter shade. The nacre is notably iridescent, lustrous, and 

 translucent in Lloyd's Devil's liiver specimen. 



Unio umbrosus Lea. 

 Mexico, ill the Rio Salado, near Leon, January, 1891, William Lloyd (Mus. No. 20919). 



A single large, heavy example, exceeding in size and weight the largest 

 in the Lea collection. Dr. Lea's specimens were from the Medelliu River, 

 Mexico. 



Unio camptodon Say. 



= 17. manuMus Gould. 

 = U. symvietricus Lea. 

 -\-U. jamesianiis Lea. 



Texas, Sons Creek, Los dos Ilcrnianos, November. 1890, William Lloyd (Mns. No. 

 120921). 



In the three examples collected by Mr. Lloyd we have the aspect of 

 camptodon to which Mr. Lea gave the name symmetricus. Of the four 

 specilic names, Mr. Say's has priority; as to the propriety of regarding 

 the others as synonyms, there is no question in the face of a comparison 

 of the specimens in the national collection. 



A varietal position is the utmost that can be conceded to these so- 

 called species. The distribution of the Ibrm or forms of camptodon is 

 principally southern. Without presenting in this place an exhaustive 

 exhibit of localities as shown by the material in the national collection, 

 lit is sufficient to state that the first, camptodon^ has been collected and 

 credited to southern Illinois, in the north. Say described it from New 

 Orleans, Louisiana; Gould's mamihius, to Chihuahua, Mexico; Lea's 

 symmetricns, to Red River, Louisiana; and the same author's Jamm- 

 \anns, to Jackson, Mississippi. 



Margaritana margaritifera Linn. 



INevada, East Hnmboldt River, October, 1890, Vernon Bailey (Mns. No. 120349); 

 California, Plumas County, W. IT. Dall (Mns. No. 1185.^)9). 



A single examjde, with nacre bluish to reddish purple, collected by 

 Mr. Bailey. Mr. Dall collected specimens in the Sierra Nevada, near 

 De%il's Corral, Plumas County, California, at an elevation of 5,200 

 feet above the sea. The nacre a dull purple. 



It is interesting to note the hypsometrical distribution of this wide- 

 spread form which is found geographically dilfused over the north- 

 ernmost portions of the three continents, Europe, America, and Asia. 

 It reaches an altitude higher than any of the tooth-hinged freshwater 

 mussels, and in this feature of its distribution equals a few of the 

 Anodons. Mr. Dall's specimens, I am inclined to believe, are from a 

 2;Teater altitude than heretofore reported. 



