Distribution of North American Viviparidce. 139 



eastern Iowa and portions of Illinois and western Indiana it is 

 an abundant shell in ponds and bayous being rarely found in 

 the more swiftly flowing rivers. 



The most restricted species of the genus is Vivipara troos- 

 tiana Lea described from Tennessee. The original locality 

 was unknown to Lea who described it as having been received 

 from Dr. Troost. I found it abundantly in a small stream at 

 Murfreesboro and think it possible that this was the original 

 locality. It has been found at no other place so far as we 

 know and is still the rarest Yiviparid in all our collections. 



The form known as Vivipara subpurpurea Say is found 

 over all the Mississippi valley from Caddo Lake, Texas, to Ft. 

 Snelling, Minnesota ; thence it ranges eastward into western 

 Indiana. In the Mississippi river at Davenport and in the St. 

 Francis river, at Wittsburg, Arkansas, it attains the maximum 

 of numbers. It has somewhat the habit, at Davenport, of 

 Tulotoma being very common under large flat rocks in the 

 Moline rapids. In the more southern localities it is, like most 

 of its congeners, a mud-loving form. 



The facts connected with the hypsometric or vertical distri- 

 bution of the Viviparidce are relatively few in number and 

 may be briefly recited. Of the localities from which we have 

 seen specimens or of which we have any authentic record 

 most of them lie between 100 and 700 feet altitude. The 

 species which has greatest vertical range is Campeloma decisum 

 which is reported from Hiram, Ohio, at an elevation 1260 feet. 

 Many localities ranging from 500 to 800 feet altitude have been 

 noted ; but this one gives the greatest vertical range observed 

 up to the present time. This genus has the greatest geo- 

 graphic range and it is not surprising that it should also furnish 

 examples of extreme hypsometric distribution. From this 

 altitude it extends downwards to sea-level or with 10 feet of it 

 at Stonington, Ct., and several localities in New Jersey. 



Campeloma stihsolidum has the next highest distribution, 

 specimens having been taken from the Des Moines river, Iowa, 

 at Fort Dodge, at an elevation of 1100 feet. Campeloma 

 coarctatum ranges to 890 feet, reported from Sedalia, Mis- 

 souri. It ranges downwards to within 20 feet of sea-level as 

 near the city of Natchez, Mississippi. Campeloma mufum has 

 been reported from only one locality which reaches 1000 feet 

 altitude, namely at Akron, Ohio. The same fact is true for 

 Campeloma ponderosum which has its greatest vertical range 

 at the same place. Campeloma integer has never been taken 

 at an elevation greater than 735 feet, which locality is the St. 

 Joseph river, at South Bend, Indiana. Campeloma decisum 

 geniculum has been found at Athens, Georgia, at an elevation 



