78 THE NAUTILUS. 



from a very careful study of the original description in com- 

 parison with quite a large series of both compressa and tappani- 

 anus, that a strong argument could be made tending to show 

 that, on the whole, as between -these two forms, viridis should be 

 approximated to tappanianus rather than to compressa. But the 

 burden of proof is upon those, who advocate the change and 

 until a prima facie case has been presented in favor of the change, 

 there is no occasion to go into that question. 



6. In view of the fact that nothing is known of the fauna of 

 the Kentucky so far as this group is concerned, it would seem 

 quite within the bounds of possibility that there may be a form 

 of this group in the Kentucky, which is neither compressa nor 

 tappanianus, but allied to the quadrata Lea or diversus Con., 

 and which may be the real type of viridis. This may be a 

 mere possibility, but even so, it emphasizes the importance of 

 ascertaining what the fauna of that river really is. 



Taking all these elements of doubt into consideration, it would 

 seem to me that so far as the compressa of Lea is concerned, no 

 change in the accepted nomenclature should be made until it 

 can be based upon facts so conclusive as to put an end to dis- 

 cussion. 



For the benefit of the "weak-kneed", who, like myself, 

 hesitate to accept Mr. Frierson's conclusions, it may be well 

 to call attention to the fact that Mr. Frierson is in error in 

 his statement that if Rafinesque's name be not accepted, Lea's 

 name of compressa must give way to the alasmodontina of Stimp- 

 son. Lea originally described his species as Symphynota com- 

 pressa. The fact that an author errs in the generic reference of 

 a new species does not prevent the use of his specific name in the 

 genus to which the species properly belongs, provided, of course, 

 that his name has not already been used for an earlier described 

 species in that genus. Mr. Frierson assigns the species to Las- 

 migona, in which there is no other species described as compressa. 

 It follows, therefore that the " weak-kneed ' : will still continue 

 to use Lea's name for this species until it is proved to be a syn- 

 onym of some earlier name. 



