THE NAUTILUS. 125 



Tryon are individual variants of the same species. Whether 

 the Alabama race should be considered simply a variety of the 

 typical ponderosum of the Mississippi system or be given speci- 

 fic rank is largely a matter of individual opinion. Dr. Lewis 

 was evidently, at one time, inclined to consider them specific- 

 ally distinct, but his latest opinion was, apparently, different. 

 Personally I am inclined to consider them local races of a com- 

 mon species. 



The name that should be used for the Alabama race presents 

 an interesting question. Incrassata and coarctata were not only 

 described at the same time, but both descriptions were pub- 

 lished on the same page, incrassata preceding coarctata. If the 

 rule of priority applies to page precedence, it would be neces- 

 sary to use Lea's first name, incrassata. But this would be very 

 unfortunate ; for the specific type would be an immature, de- 

 formed and depauperate example. On the other hand, while 

 the type of coarctata is also a young shell, it is, nevertheless, a 

 perfectly normal one and represents the species much more cor- 

 rectly. It is, therefore, very desirable to use that name, if it 

 can be done without violating the provisions of the International 

 Code. On referring the question to Dr. Pilsbry, he replies : 



"In this kind of a case, it is held that the first reviser may 

 select which name may hold. Jordan and some others consider 

 position on a page as giving "precedence," a view which has 

 been vigorously combated and which has not been supported 

 by the International Committee on Nomenclature, who hold 

 that all names on one page, or indeed in one work, were pub- 

 lished simultaneously (see Opinion 40 of the International Com- 

 mittee on Nomenclature). Personally I believe in Jordan's view, 

 as an artificial precedence is better than no rule. You have, 

 however, the right to decide either way under the rules". 



Under this opinion and for the reason above given, I select 

 "coarctata Lea" as the name to be used for this form. 



The synonymy, therefore, becomes as follows : 

 CAMPELOMA PONDEROSUM COARCTATUM (Lea). PI. V, figs. 4-7. 



1843. Paludina coarctata Lea, Pr. Am. Phil. Soc., II, p. 243. 



1862. Vivipara coarctata W. G. Binney, Desc. Cat., p. 30, 

 figs. 50-51. 



