126 A MANUAL or AMEKJCAiN LAND bHELLS. 



teeth. I found the poiuts, however, iu A. rnjicincia (Plate IX, Fig. N). 

 A. Tow7ismdiana (Plate IX, Fifj. Q) has these cutting points and side 

 cusps on central and all the lateral teeth; Its centrals and laterals are 

 not of the same shape as described above, but resemble those of Poly 

 gyra, Stenotrema, and Triodopsis. Thus in this as in other genera we 

 find the type of dentition not constant in all the species. 



The long, narrow base of attachment and pyriform reflection in the' 

 lingual teeth of most of the species of Arionta agree with those of 

 Hemitrochus more nearly than an\ other of our genera, but that genus 

 has quite different marginal teeth. 



The dentition of A. arhustornm is alone known of the species foreign 

 to America, and that by a figure of Lehmanu (Lebenden Schnecken, 

 Plate XI, Fig. 29) too unsatisfactory to be of value for the purpose of 

 comparison. 



The geographical distribution of the species is very peculiar. A. 

 Townsendiana belongs to the Oregon fauna. I doubt its ever having 

 been found in Tuolumne County, California. A. Mormonum belongs to 

 the Sierra Nevada counties, asVlues A. tudiculata, which also is found 

 in southern coast counties. All the others are restricted to the coast 

 counties, ranging as stated in the text, the following being island 

 species : A. rujicincta^ Gahbi, intercisa, Ayersiana, and Kelletti. A. 

 Stearnsiana and Carpenteri are Lower Californian species. 



The genitalia are the same in arrosa, exurata, Kickliniana, Diablo- 

 ensis, Californicnsis, Ayersiana, tudiculata, TrasM, Carpenteri, sequoicola, 

 Siud Dupetithoimrsi. From these the genitalia of Mormonum differ very 

 essentially, being more nearly allied to those of Aglaia fidelis and in- 

 fumata. A. Townsendiana has simple genitalia, without the accessory 

 organs usually found in Arionta. A. Kelletti and Stearnsiana have the 

 organs still more complicated with accessories. A. rujicincta and Oabbi 

 are related by their genitalia to the last, but differ considerably in 

 wanting the accessory duct of genital bladder. A. redimita has geni- 

 talia as in Euparyplia Tryoni. *= 



Arionta arrosa, Gould. 



Shell globose-conic, thick, umbill^ated, indented, and minutely gran- 

 ulated ; color reddish-olive, varied with yellow, and with a fuscous re- 

 volving band; whorls 7, convex; aperture roundly ovate; peristome re- 

 flected, flesh-colored ; throat bluish. Diameter, 40™""; height, IS"*"", 



