40 CATALOGUE FAMILY UNIOXID^E. 



* Uiiio occidens, Lea. 



(Trans. Am. Phil. s O c., Vol. Ill, PI. X, Fig. 16.) 



This species has a very wide range, is common wherever it occurs, and is a 

 member of the large group typified by U. ovatvs, Say. It ranges from Ottawa 

 river, Canada, to Western New York, Pennsylvania and Ohio; southwest to 

 Indian Territory and north to Nebraska and Minnesota. ' In the belief that this 

 form is synonymous with 77. ventricoxns Barnes, that name has been affixed to 

 all specimens distributed by the reporter. Say evidently so regarded it inas- 

 much as his figure of ventricosus (Descriptions of the shells of North America, 

 PI. XXXII.) appears to be identical with Lea's figure of occidtns. The beau-, 

 tifully rayed specimens, such as served for the illustrations oi both Say and Lea, 

 are exceptionally rare, and do not represent the form as commonly found. 

 With this form group 77. capax and 77. canadensis. 



\ Unio oceidentalis, Conrad. 



(Monogiaph of Unio, PI. XXXVI, Fig-. 1.) 

 " Currant river, Arkansas." 



*TJnio orbiculatus, Hildreth. 



(For illustration reference see 77. hiaginsii, Lea.) 



Eanges southwest from the Ohio to the Cumberland, west to Davenport, Iowa, 

 and Blue river, Kansas. See under 77. Myginsii, Lea. 77, pinyuis groups here, 

 and is probably synonymous. 



t Unio ovatus, Say. 



(Am. Jour, of Sci and Arts, 1st Series. Vol XIV, PI. I, Fig-s., 21a, 21b. Also well figured 

 by Lea as 17. excavatus.) 



This is the type of a very large gioup of widely distributed Unirmcs. It 

 anges from the Alleghany river to Central New York and south to the Tennes- 

 see and Holston rivers. In the Black Warrior, Alabama, Cahawba and Coosa 

 rivers, Alabama, is a very closely related form, which passes under the name of 

 77. excnvdtus. 



tUnio oviformis, Conrad. 



(New Fresh Water Shells of the Unit< d Stti'os, PL III, Fig-. 6.) 

 Clinch river, Tennessee. It belongs to the gvcup of argmtius. 



CATALOGUE 32. 



