l82 UNIVERSITY OF COLORADO STUDIES 



<^-^2> Planorbis exacuous Say. Fig. 43. 



*"~~« A few specimens were found by Mr. D. M. Andrews in a small lake 



Fig. 43- Plan- between Magnolia and RoUinsville, in the mountains west of Boulder, 

 orbis exacuous. ° 



Genus ANCYLUS Geoffroy 



Ancylus fragilis Tryon. 



On boulders in Buzzard Creek, Cockerell 22, 65. 



Ancylus parallelus Hald. Fig. 44. 

 North Park, IngersoU 35, 405. 



Fig. 44. — An- 

 cylus parallelus. 



Ancylus caurinus Cooper. Fig. 45. 



Collected by Prof. D. W. Spangler in the St. Vrain at Longmont 



Pjq ^j fi^. and by the writer in the Big Thompson at Loveland, identified by 



cylus caurinus. j)j.. Bartsch. One specimen was collected at Ft. Collins by Mr. 



L. C. Bragg, in Februarj', 1907, and sent to us for identification. This species may 

 be considered fragilis, however, as some conchologists consider the two nominal species 

 the same. 



Genus PHYSA Draparnaud 



The Genus Physa is in a very unsatisfactory condition. The species are diflBcult 

 to distinguish from each other, quite variable in form and otherwise, many early descrip- 

 tions indefinite and early records doubtful. Our experience has been that in submitting 

 collections of Physa to different conchologists they will always differ in their identifica- 

 tions of many of the specimens, and all would like to see some genius with sufficient 

 time, material, energy and courage monograph the genus, examining the types so far as 

 possible. The records which follow are submitted with considerable hesitation, and we 

 would not for the world urge anyone to accept them without question. 



Physa heterostropha Say. 



Hot Sulphur Springs, east of Saguache and between Animcis and LaPlata, Inger- 

 soU 35, 400. Pueblo, Yarrow 68, 938. Canyon City, Empire, Hot Sulphur Springs, 

 Middle Park and Denver, IngersoU 37, 133. Rio Grande and Gunnison River, small 

 variety at West Cliff, Cockerell 22, 63, 64, 65. 



It is quite possible that many or all of these records are erroneous. Until the genus 

 is revised by some one with plenty of time and abundant material it is not safe to say 

 much about the various species, and particularly is this true of the early records. We 

 obtained specimens at Hamblin's Lake, near Hygiene, which Dr. Bartsch assigns to this 

 species. 



Physa wolfiana Lea. 



Hot Sulphur Springs, described from specimens found in the hot water, but assigned 

 by IngersoU to heterostropha, IngersoU 35, 401. 



Mr. Bryant Walker writes that he has specimens from the Hot Springs, but that 

 whatever they are, they are not heterostropha. Specimens coUected by the writer at 



