Occasional Papers of the Museum of Zoology ^9 



Unio biangnlaris Lea, '40, p. 288. 



Unio biaiigulatus Lea, '42, p. 197, pi. 9, f. 8. 



LampsiUs biaiigularis (Lea), Simpson, "14, p. 59. 



Lampsilis perdix (Lea), Simpson, '14, p. 88. 



Nephronaias pectorosa (Con.) ^= t/. perdix Lea = C7. hiangularis 

 Lea ^ [/. biangulatus Lea =: (possibly) U. znttatis Raf., Ortmann, '18, 

 P- 569. 



U. vittatis Raf. would have priority, if identifiable. Its shell 

 is oval and has been compared by Rafinesque with L. fasciola 

 Raf., but is said to be larger, rounder, with straight rays. 

 This does not fit pectorosa, which surely is not "rounder" than 

 fasciola, and there are additional characters in the original 

 description which cannot be reconciled with pectorosa, chiefly 

 "2 or 3 oblique ribs." U. zittatis is not identifiable. 



It has been questionably referred to iniiatus and siliquoideus 

 Bar. by Conrad ('34, p. 69). 



The identity of Conrad's and Lea's species is evident to any- 

 one familiar with this form, and the preference of perdix by 

 Simpson is due only to the incorrect date given for it. Already 

 Conrad ('36) has claimed his species and has quoted the cor- 

 rect dates. 



Genus Truxcii^la Rafinesque, 1819 



Type: Truncilla trimcata Raf. 



Triiiicilla Rafinesque, "19, p. 427; '20, p. 300 (no type named) ; Herr- 

 mansen, '49, p. 627 (type, Truncilla trimcata Raf.). 



Atiiygdaloiiaias Crosse and Fischer, '93, p. 557 (type, U. cognatiis 

 Lea); Simpson, '00, p. 604; Ortmann, '12, p. 327. 



Since Tr. truncata Raf. (^ elegans Lea) is supposed to be 

 congeneric with U. cognatus Lea, and since Herrmannsen has 

 designated trimcata as the type of Truncilla, this name will 

 have to be used for the present genus superseding that of 

 Auiygdalonaias. 



This will necessitate a change in the name of the genus which 

 has been usually called Truncilla. See under Dysiiomia. 



