Call — The Unionidce of Arkansas. 63 



The group has received too little attention, and too much re- 

 liance has been placed upon authority to fully and correctly 

 understand this shell. Those who collect Unionidce by proxy, 

 and whose acquaintance with streams and lakes is confined to 

 the views from passing train or from study window, will 

 continue to see many species in this polymorphous form. 



Specimens were obtained in the St. Francis river, at Witts- 

 burg, and in the Saline, at Benton. It will doubtless be found, 

 in numbers, in the old river beds of all the larger streams, and 

 in most ponds and lakes throughout the State of Arkansas. 

 It ranges to western New York and to central Texas, and 

 north to British America. 



Anodonta imbecillis Say. 



New Harmony Disseminator of Useful Knowledge, 

 1829, Vol. II, No. 23, p. 355 ; Reeve, Conchologia Iconica, 

 Vol. XVII, Anodon Plate XXVII, Fig. 102, as of Lea. 

 Described from the Wabash river. 



Anodonta incerta Lea. Trans. Am. Philos. Soc, Vol. 

 V, 1832, p. 45, PI. VI, Fig. 16; Reeve, Conchologia 

 Iconica, Vol. XVII, Aiiodon Plate XVII, Fig. 59. 

 Described from the Ohio river. 



Anodonta Jtordea Gould. Proc. Bost. Soc. Nat. Hist., 

 Vol. V, 1855, p. 229; Reeve, Conchologia Iconica, Vol. 

 XVII, Anodon PI. XVIII, Fig. ^Q, as Anodon hordeum 

 Gould. Lea says this is Say's Anodonta imbecillis; it 

 must be confessed that Reeve's figure bears no resem- 

 blance to it as it is generally understood on this side of 

 the Atlantic. 

 There is no Anodonta in American waters so easily de- 

 termined as this one, and so little likely to be confounded 

 with any other species. It is commonly of a bright green 

 color, and is of very thin texture, resembling nothing else in 

 our waters. In Arkansas it has been found only in the St. 

 Francis river, at Wittsburg, but doubtless occurs elsewhere. 

 We have it from various localities in Louisiana and Texas, 

 whence it ranges to western New York and Canada. 



