^°l89i!^'] PROCEEDINGS OF TilE NATIONAL MUSEUM. 103 



Planorbis tuniidus Pfr. 



Texas, Devil's litvor, several examples (Mus. No. 118396), William Lloyd. 



Planorbis liebmani Dkr. 



Texas, Devil's River, one specimen (Mus. No. 118398), William Lloyd. 



Planorbis (Gyraulus) parvus Say. 



Arizona, Walker's Lake (Mus. No. 103625), Dr. C. Hart Merriam ; Devil's River 

 (Mns. No. 118397), W. Lloyd. 



A single example of this characteristic species was found among 

 the numerous specimens o^ Linncca nutfalliana collected by Dr. Mer- 

 riam in the crater bowl of Walker Lake, San Francisco Mountain, 

 during his biological exploration of the region in 1889, The national 

 collection also contains examples from this territory, collected by Dr. 

 Edward Palmer, and General Carlton collected it on the Colorado 

 Desert, California,wliere also I detected it near Indio and at other places 

 along the line of the Southern Pacific Railroad, in 1884. 



Physa heterostropha Say. 



Arizona Territory, at riinenix (Mas. No. 100851); Magdalcna, Xortliwest Mexico (No. 

 103622); Idaho, Birch Creek (No. 120347) ; Nevada, East Humboldt River (Mus. 

 Nos. 120907 and 120908), Vernon Bailey. 



Several examples, for the most part immature, were obtained at 

 Phoenix by Mr. Bailey, who detected them in an irrigation ditch " among 

 moss." The Mexican examples were also found in a similar situation. 



In the course of its southerly distribution this widely diffused form 

 has been the recipient of many specific names, apparently induced more 

 by the occult influence of politico-geographical lines upon the describer 

 than any special differential facies of the shells themselves. 



From other southerly regions the Museum series indicates the follow- 

 ing localities: Hot Springs, Lower California (Xo. 47753), IT. & C. K. 

 Orcutt, March, 1882 ; Mexico, Puebla, Puebla ; and Mizantla, Vera Cruz, 

 Mexican Geographical Commission. 



The Nevada specimens collected by Mr. Bailey (No. 120907) were from 

 Elko. Of these there are several examples, some of which approach 

 the form named amimllacea by Dr. Gould. The specific name hetero- 

 stropha was published by Say in 1817 under ii»ma'«. Subsequently, in 

 1821, P. gyrina was described and published. 



A large series demonstrates that these alleged species interblend and 

 merge the one into the other, so that the application of one of these 

 names more than the other is altogether arbitrary or capricious ; but as 

 heterostropha has four years' prioritj^ over gyrina, the former name must 

 supersede and include the latter, as well as a great many other specific 

 names at present in use, whenever a revision of this group is made. 



Physa gyrina Say. 

 Texas, Pecos River, near Painted Cave (Mus. No. 118387). William Lloyd. 



Three fresh and perfect specimens. 



