70 A MANUAL OF AMERICAN LAND SHELLS. 



Helix ruderaia, Adams, Sill. Jour, [i], 40, 408, not Studer. 



Belix CronkhUei, Newcomb, Proc. Cal. Acad. Nat. Sci., iii, 180 (1865). 



Patula siriaiella, Morse, Journ. Portl. Soc, i, 21, fig. 48, pi. ii, fig. 6; pi. viii, fig. 49 



(1864).— W. G. BiNNEY, T. M., A', 105. 

 Anguispira striatella, Tryon, Am. Journ. Couch., ii, 262 (1866). 

 Patula Cronkhitei, Tryon, Am. Jouru. Concli., ii, 263 (1866)! 



This species is found through British America, at Great Slave Lake, 

 Canada, &c., New England, and extends to Virginia and Kansas. It 

 has also been found in Arizona, Idaho, at Hell Gate Eiver, Nevada, Colo- 

 rado, in the Central Province, and has been quoted from the Pacific 

 Province at Mariposa, Cal. It may, therefore, prove to be universally 

 distributed. Middendorf refers it, as distinct from pauper, to Kam- 

 chatka and Northern China. 

 Jaw arcuate ; ends attenuated ; anterior surface with converging 

 no '29. striae ; concave margin irregularly notched, no 



median projection (Fig. 29). 

 Lingual membrane with 100 rows of 16-1-16 

 j.nvoip.stnateiia. (Morse), ^.^^^i^ (Morsc), The liugual examined by mc (T. 



M., V, Plate IV, Fig. B) has 20-1-20 teeth, with 8 perfect laterals. 



Animal: Head, neck, and eye-peduncles dusky; foot white. 



Genitalia unobserved. 



As regards P. CronMitei, I am not able to decide about its specific 

 distinction from striatella. Specimens, one of which is here figured, 

 have been sent me under this name from Unalashka, from Klamath 

 Lake, and various localities in the Pacific and Central Provinces. I 

 have also been able to study the original specimen in the collection of 

 Dr. Newcomb. It is larger, of a lighter color, and has coarser striae 

 than the typical striatella, and agrees with the shell I have figured as 

 CronMitei. 



P. striatella bears a very strong resemblance, in general aspect, to 



riG. 30. perspectiva, with the immature shells of which it is very com- 

 monly confounded. It needs some attention to separate the 

 two, but when the present species is once noticed, it cannot 

 fail to be considered very distinct. Its discriminative char- 

 acters, as compared with the former species, are as follows: 

 r. Cronkhitei. The mature shell is smaller, and has generally rather less 

 and never more than 4 whorls; and in shells of the same size the num- 

 ber of volutions is less. It is thinner and more delicate; its color is 

 lighter; its striai of increase are more numerous, more oblique, much 

 finer, and less prominent; its suture is less deeply impressed; its spire 

 is more convex, and its umbilicus less expanded. The character of the 



