THE NAUTILC&. 



Melampus flavus Gmel. Abundant. 



These shells were not intermingled with marine forms, which 

 strew the shore on both sides of the peninsula. The identifications 

 are by Bryant Walker. 



ON THE VALIDITY OF UNIO TTNDATTJS BARNES. 



BY BRTANT WALKER. 



This species, which is apparently easily identifiable, has been 

 buried in the synonymy for over half a century. A careful study 

 both of the literature and of a considerable amount of material has 

 convinced me that it is entitled to recognition as a valid species. 



The synonymic history of the species is, briefly, aa follows ; It 

 was described by Barnes in 1823 (Am. Jour. Sci. VI, p. 121, pi. IV, 

 fig. 4) and was based on specimens collected by Schoolcraft in the 

 Wisconsin and Fox rivers. 



In 1828, Hildreth (Am. Jour. Sci. XIX, p. 280) recognized the 

 species among the Unionida of the Muskingum river, Ohio, and as 

 his paper was submitted to Barnes before publication, there is ap- 

 parently no doubt but that his identification was correct. 



In his first attempt at an arrangement of the North American 

 Unionidse in 1829 (Obs. I p. 32) Dr. Lea considered it as a synonym 

 of U. mytiloides Raf. 



In 1833, (Obs. I p. 200) after his return from Europe, where he 

 had studied the Lamarckian types, he declared Barnes' species to be 

 the same as U. obliquus of that author. 



In the meantime, in 1831, Lea (Tr. Phil. Soc. IV. p. 110 pi. XVI 

 fig. 40) had described his Unio trigonus from the Ohio as a new 

 species. 



It is to be noted that Barnes died in 1828 before trigonus was de- 

 scribed, so that he was not able to express his opinion as to the 

 validity of Lea's species. 



In 1834, Conrad in bis Synoptical Table " (New F. W. Shells 

 p. 72) considered the two species as synonymous and gave undatus 

 priority. 



In the same year, Say in his " Synonymy " (Amer. Con. Pt. VI) 

 did the same. 



Ferussac in 1835 (Guer. Mag. I p. 28), after Dr. Lea had visited 



