170 BULLETIN OF THE 



account of its very r'cpressed form and the ovate form of the aperture, the heavy 

 callus joining or "yoking" togetlier the extremities of the peristome. 



The above is Hemphill's description. 



The figure in the Third Supplement is drawn from an authentic specimen. 



Patula strigosa, Gould, var. intersum, Hemphill. 



Shell umbilicated, sublenticular, depressed, thin, dark horn-color, more or less 

 stained with darker chestnut. Wliorls 5| or 6, somewhat flattened above, more 

 corvev beneath, obtusely carinated at the peripher}', and bearing numerous coarse 

 oblique rib-like striae, and two dark revolving bands; suture well impressed; um- 

 bilicus large, pervious ; aperture oblique, subangulated ; peristome simple, thick- 

 ened, its terminations joined by a thick callus. Heiglit of the largest specimen -J 

 inch, breadth | inch. Height of the smallest specimen fg inch, breadth ^^ inch. 



Patula strigosa, var. intersum, Hemphill, The Nautilus, 1890, p. 135. 



Bluffs along the banks of Little Salmon Eiver, Idaho. 



This shell inhabits stone piles at the foot of a steep bluff back some distance 

 from the river. It seems to be quite rare, as I found but few specimens during 

 the two or three days of my stay in its vicinity, and many of them were dead. I 

 regard it as one of the most interesting shells found by me during tlie season, for 

 it combines the depressed angulated or keeled forms of the Haydeni side of the 

 series with the sculpturing of Idahoensis, two shells representing opposite charac- 

 ters in every respect. It thus becomes the companion of Wahsatchensis, a beautiful 

 shell, combining the same characters, but much more developed, and connected 

 with the large elevated forms. Var. intersum fills the opposite oflBce, by uniting 

 these characters with the small depressed forms. Taken as a whole, this series of 

 shells, as now completed, seems to me to offer the best guide or key to the study 

 of species that the student can have. Every known external character belonging 

 to the genus Helix is so gradually modified and blended with opposite characters, 

 that, if one had the moulding or making of the many and various intermediate 

 forms, he could scarcely make the series more complete than Nature has done 

 herself. 



The above is Hemphill's description. 



Patula strigosa, Gould, var. globulosa, Cockeeell. 



Small, globose, dark above periphery, with two bands, transverse grooved striae 

 rather well marked. Diameter lU, alt. 8i mm. Black Lake Creek, Summit Co. 

 The specimen seems immature, but is remarkable as being the onlj' form I have 

 seen in Colorado that is nearer to strigosa than Cooperi. It is doubtless allied to 

 var. Gouldi, Hemphill. (Cockerell.) 



Patula strigosa, var. globulosa, Cockerell, The Nautilus, 1890, p. 102. 



The above is Cockerell's description. 



The above varieties of Patula strigosa are transversely ribbed. The following 

 are smooth or striate 



