PILSBRY: non-marine MOLLUSCA of PATAGONIA. 52I 



"Longit. 12 mm. Lat. 7.3 mm. AperturaS mm. longa, 5^ mm. lata." 



Dr. Doering's description and figures apply fairly well to a Skcciucu of 

 the S. avara group, which is abundant and widely distributed in the ter- 

 ritory of Santa Cruz, collected at the following stations : 



Near Mt. of Observation (near the coast, south of Santa Cruz River). 



Near Pescadores, south side Santa Cruz River, 15 miles above mouth. 



Spring on Rio Chico, above mouth of Rio Chalia. 



Spring on Rio Chico, north side, near Sierra Ventana. 



Spring on Rio Chico, 7 miles above Sierra Ventana. 



Spring near Sierra Oveja. 



Springs on Rio Chico, 15, 40 and 50 miles above Sierra Oveja, and 25 

 and 15 miles below confluence of Rio Belgrano. 



Stream near mouth of the Rio Belgrano. 



Base of Andes, 40 miles north of Rio Chico, 2000 feet elevation. 



Base of Andes, 50 miles north of Rio Chico, 1750 feet elevation. 



Base of Andes, 65 miles north of Rio Chico, 2400 feet elevation. 



Pool near Arroyo Eke, near head of Spring Creek, elevation 1750 

 feet. 



Specimens from a spring 7 miles above the Sierra Ventana, "on horse 

 dung near the water," are figured, PI. XLII, figs. 4, 5. 6. The color varies 

 from honey-yellow to whitish-yellow, always with the first whorl of a 

 deeper yellow shade. The suture is very deep and the whorls extremely 

 convex. The specimens figured measure : 



Length 11, diam. 6 mm., length of aperture 6.5 mm.; whorls 31^. 



II " 6.9 " " " 7.25 " " 2>%. 



" 12.3 " 6.9 " " " 7 " " 3%. 



It will be noted that, as compared with Doering's description, these shells 

 have the aperture shorter. 



At all other stations the shells are smaller. Two figured from the Rio 

 Chico 50 miles above Sierra Oveja (PI. XLII, figs. 2, 3) representative of 

 this small form measure : 



Length 7.9, diam. 4.9 mm., length of aperture 5 mm.; whorls y^i . 

 " 7.5 " 4 " " " 4 " " 2>}i . 



In a series of fossil individuals from the banks of a stream 10 miles from 

 Ushe Lake (collected January 14, 1898), there is remarkable variation in 

 contour, though most of the shells are much lengthened. 



