76 THE NAUTILUS. 



My reasons for asking a suspension of judgment in this case 

 are, briefly, these: 



1. Rafinesque states explicitly that his wndis was "rare in 

 the Ohio, more common in the Kentucky and the small rivers 

 adjacent". So far as I have been able to ascertain, no species 

 approximating in any way to viridis, compressa or tappanianus 

 has been recorded from the Ohio, the Kentucky or the small 

 rivers adjacent. As a matter of fact, we know practically no- 

 thing of the Naiad fauna of the Kentucky, where, if anywhere, 

 the genuine viridis should be rediscovered. And until the fauna 

 of that river has been carefully investigated and it is definitely 

 determined what species, if any, of this group is found there, 

 it would certainly seem the ' ' better part of wisdom ' ' to suspend 

 hypothetical identifications of the species. 



2. The compressa of Lea is most emphatically a creek or small 

 river species, ranging from western New York and Pennsylvania 

 west to Iowa and north to the Missinaibe River in the Hudson 

 Bay region. I have not been able to find any definite record 

 of its occurrence in the Ohio. Dr. Ortmann, (Ann. Car. Mus., 

 V, 1909, p. 196), states that in western Pennsylvania, it is 

 "entirely absent in the Ohio", and, (Pr. Am. Phil. Soc, LII, 

 1913, p. 296), that it is "a peculiar form restricted to the tribu- 

 taries of the upper Alleghany and also in French Creek and 

 Beaver River drainage". If not found in the upper reaches of 

 the Ohio, it is not likely that it occurs in the deeper waters of 

 the lower pertions of the river. 



The only record of its occurrence in any of the southern tribu- 

 taries of the Ohio is that of Dr. Ortmann, (Pr. Am. Phil. Soc, 

 LII, 1913, p. 372), from the little Kanawha River, which 

 empties into the Ohio at Parkersburg. 



So far as I have been able to ascertain, it has never been listed 

 from any of the tributaries of the Ohio in Kentucky or Tennes- 

 see. Apparently, with the exception above noted, so far as our 

 present knowledge goes, the Ohio has been a barrier to any 

 extension of this species into its southern tributaries. 



If Rafinesque' s statement as to the locality of his species is 

 to be relied upon, in view of these facts it does not seem too 

 much to ask that the actual occurrence of compressa in the Ken- 



