Call — TJie Unionidce of Arkansas. 25 



Say's description of Unio crassus does not agree with his 

 figure, as has already been pointed out by Dr. Lea. He says 

 his species has waves, while the figure, which shows the 

 interior of the shell only, does not give any hint of that char- 

 acter. It is doubtful that the description and figure were 

 made from the same species. Moreover, it will be noticed, 

 from the dates assigned to these several forms in the synonymy, 

 that Say's species was described long before Lamarck framed 

 his description. But there had already been described from 

 Europe, by Retzius, 1788, a species with the name Say em- 

 ployed. Say's name, therefore, falls into synonymy. This 

 shell is often received from correspondents under the name of 

 Unio luteolus Lamarck, which form it very closely, in some 

 respects, resembles. 



The Arkansas localities, whence the species has been 

 obtained, are the St. Francis river, at Wittsburg ; Ouachita 

 river, at Malvern ; and Saline river, at Benton. The last 

 named stream is the original one for the shells which Lea 

 described under the name of Unio powellii , the female of which 

 is well figured by Reeve in the volume cited. His specimen 

 was a fair exhibition of the Arkansas form. 



Unio luteolus Lamarck. 



Plate HI. 



Animaux sans Vertebres, 1818, Vol. VI, p. 79; also, 

 same, edition of 1838, Vol. VI, p. 544. 



Unio luteolus Lamarck, Reeve, in Conchologia Iconica, 

 Unio Plate LVIII, Fig. 239, female ; 239b, female, 1867 ; 

 also, in same, Plate LXI, Fig. 306, as Unio multiradialus 

 Lea, corrected in errata. This is a good figure of the 

 female. 



Unio siliquoideus 'Barnes. Am. Jour. Sci. and Arts, 1st 

 series, Vol. VI, p. 269, Fig. 15, 1823. This is female 

 luteolus. 



Unio inflatus Barnes. Am. Jour, of Sci. and Arts, 1st 

 series, Vol. VI, 1823, p. 266. 



Unio hydianusLtea. Trans. Am. Philos. Soc, Vol. VI. 

 p. 14, PI. VI, Fig., 14, 1834; Reeve, in Conchologia 

 Iconica, Unio Plate XXXVII, Fig. 203, female, 1866. 



