132 JR. E. Call — Geographic and Hypsometric 



Art. XYII. — On the Geographic and Hypsometric Distribu- 

 tion of North American Viviparidce y* by R. Ellsworth 

 Call, Louisville, Ky. (With Map.) 



Ln" some respects these unattractive mollusks constitute a 

 remarkable assemblage of natural forms. They are not widely 

 separated in point of geological history from the Mississippi 

 valley Unionidce which, with these shells, apparently date back 

 to strata of Laramie age. Specimens referred to this genus 

 have been described from Laramie rocks in Montana, Colorado, 

 Wyoming and British America. It is more than probable that 

 from this region as a center all the recent forms have been 

 derived. 



The Viviparidce of North America are all comprised in 

 four genera. Of these the species numbers, as well as indi- 

 viduals, differ widely- The recognized natural genera are 

 Tulotoma, with two species ; Lioplax, with two species ; Vivi- 

 para, with four species ; and Campeloma, with nine species. 

 There are many synonymic names, chiefly in the Campelomoid 

 section which is the most widely distributed and is by far the 

 most abundant in individuals. Questions of priority in no 

 wise enter into the plan of this paper which has to do solely 

 with questions of geographic distribution and the hypsometric 

 range of the several forms. Yet, to prevent misconception, it 

 will be necessary to indicate the names which we believe, with 

 present information, must be applied to the members of these 

 groups. The remaining names, familiar to students of mol- 

 lusca, will be regarded as synonyms of one or another form 

 herein listed. 



With this restriction, then, it is proposed to recognize in 

 Tulotoma the following forms : 



Tulotoma magnifica Conrad. 

 Tulotoma cooswnsis Lea. 



In Vivipara the following forms will stand : 



Vivipara intertexta Say. 

 Vivipara subpurpurea Say. 

 Vivipara contectoides W. G. Binney. 

 Vivip>ara troostiana Lea. 



The genus Lioplax will comprehend the following forms : 



Lioplax cyclostomatiformis Lea. 

 Lioplax subcarinata Say. 



* Read before the Indiana Academy of Sciences, December, 1893. 



