Occasional Papers of the Museum of Zoology 47 



prominent, nearly superior ; epidermis striate, olivaceous ; 

 nacre white, iridescent, length 2-3 inch. Yet it does not posi- 

 tively indicate this species. However, in connection with the 

 generic characters given for Anihlema, the species is well 

 characterized by the terms ''dent bilobee ridee, laterale an 

 sommet/' which could not be used for any other species. Thus 

 olivaria stands. 



Rafinesque ('20, p. 288) states in substance that he did not 

 repeat the generic characters in his specific descriptions, as it 

 would make them long and prolix. But when necessar}^ as in 

 this case, they should be read into the description of the species. 



Genus Actinonaias Fischer and Crosse, 1893 



Actinonaias Fischer and Crosse, '93. p. 556 (no type named, con- 

 taining Mexican species inc. sapotalensis Lea). 



Actinonaias Fischer and Crosse, '93, p. 556 (no type named, con- 

 taining Mexican species inc. aztccoriim allied to plicatulus Charp.) 



Nephro)iaias Simpson, 'oo^', p. 591 (type, plicatulus Charp.). 



Nephronaias Ortmann, '12, p. 324 (containing 3 species, incl. sapo- 

 talensis) . 



Nephronaias Frierson, '17, p. 47 (type, plicatulus Charp.). 



Actinonaias Frierson, '17, p. 48 (type, sapotalensis Leaj ; Walker, 

 'i8e, p. 75. ' 



The final settlement of the generic names Nephronaias and 

 Actinonaias depends on the knowledge of the anatomy of the 

 Mexican type of Nephronaias (plicatulus Charp.). The anat- 

 omy of the type of Actinonaias {sapotalensis } is known (Ort- 

 mann), and since certain North American species agree with 

 this, this name should be used for them. The designation of 

 the type of Actinonaias (sapotalensis) is from Frierson. 

 Actinonaias carinata (Barnes), 1823 



Type locality: Fox River (Wisconsin). 



Unio crassus Say, '17, pi. i. f. 8 (not U. crassus Retzius, 1778). 

 Unio ligamentina Lamarck, '19, p. 72. 

 Unio crassus Say, Rafinesque, '20, p. 293. 



