102 LAND AND FRESII-WATEE SHELLS STEARNS. 



Limnaea lepida Gould. 



Idaho, Salmon River, iiaar Challis, September, 1890 (Mas. No. 120351). Morriman 

 and Bailey. 



A single example, distinctly cliaracteristic, as seen at once by a com- 

 parison with the type (Mns. No. 5541) in the national collection from 

 Oregon. 



The form, to which Lea's name NuttaUiana is usually attached, and 

 which is so abundant on the west coast in California aud the other 

 Pacific States, and which frequently attains a large size, is really a 

 maximum aspect of Gould's lepida,, and is specially noticeable for the 

 expanded or effuse aperture. As Lea's name has priority of G years, 

 it may be more proper to say that Gould's lepida is a local aud varietal 

 form of NuttaUiana. Without extending this comment further as to 

 the relationship of these v^ith pfahistris, the maiu difference as between 

 typical lepida and NuttaUiana is the more sturdy aspect and flaring 

 mouth of the latter; as to where NnttaUiana leaves off and paliistris 

 begins it would be inconvenient to demonstrate at this time. Mr. Bin- 

 uey has included Iiea's species in his synonymy of palustris, and I do 

 not hesitate to concur in this arrangement. 



Lininaea Adelinae Tryon. 



Idaho, Salmon River, near Challis, Seiitemher, 1890. Merriam aud Bailey. (Mus. 

 No. 120353.) 



Two examples hardly mature of the form to which Tryon gave the 

 above name aud agreeing with the types from near San Francisco, 

 California (Mus. No. 24879). 



Planorbis trivolvis Say, var. 



Nevada, East Humboldt River, near Battle Mountain (Mus. No. 120915), Elko from 

 the same stream (Mus. No. 1209ir)). Vernon Bailey. 



A few examples of the above, approaching the corpnlentus aspect, 

 with sharply defined incremental sculpture, were obtained at the above 

 localities. 



Planorbis trivolvis Say, var. 

 = P. plexata lugersoll. 

 Idaho, Saw Tooth Lake, October, 1890 (Mus. No. 120348), Merriam & Bailey. 



The varietal aspect is exhibited in the distorted twist in the coil of 

 the earlier whorls. This distortion, which is shown by all the exam- 

 ples, eight in number, does not continue to or affect the shape of the 

 aperture, for, curiously enough, the animal, as maturity approaches, 

 gets back, if I may use the expression, to the ordinary or symmetrical 

 plane of coil. 



Planorbis tuniens Cpr. 

 Arizona Territory, at Phoniix (Mus. No. 103023), Mr. Bailey. 



This species, described from Mazatlan siiecimens, suggests the more 

 southern texture and general facies of Pkmorbis, aud recalls P. tumi- 

 dus Pfr., so abundant in Guatemala aud Nicaragua. 



