PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 525 



Section GALBA Schrank. 

 LYMN/EA VIATOR d'Orbigny. 



(Plate XLVI, Fig. 8). 



Limnaus viator d'Orb., Magazin de Zoologie, 1835, p. 24; Voy. dans 

 1'Amer. Merid., Moll., p. 340, pi. 43, figs. 1-3. 



A species of the group of L. truncatula. The shell is small and 

 smoothish, composed of five very convex whorls, joined by a very deep 

 suture ; the aperture is oval or nearly round, more than half the length of 

 the shell. The axis is very distinctly umbilicate. Length 8, diam. 4 mm. 



d'Orbigny records this species from the banks of the Rio Negro, 41 S. 

 lat, 7 or 8 leagues above the mouth, very abundant. This may be con- 

 sidered the type locality. Afterwards he collected it also at Santiago, 

 Chili, and at Callao and Lima, Peru, in irrigation ditches. The speci- 

 mens from Peru, he notes, are constantly more elongate than those of 

 Patagonia and Chili, with the whorls more deeply separated. Dr. W. H. 

 Rush collected many specimens in a creek in the Prado, at Montevideo, 

 Uruguay. These specimens, with others from Lima before me, do not 

 seem separable from the Antillean L. ctibensis Pfr. (1840) by any character 

 in the shells. 



Specimens from a pool on the bank of the Rio Chico, a mile west of 

 the Sierra Oveja (PI. XLVI, fig. 8) are larger than those from Uruguay, 

 the individual figured measuring length 10, diam. 5.1, length of aperture 

 5 mm., whorls 5^. The spire is longer, and the umbilicus somewhat 

 narrower. The columellar margin is broadly revolute and without fold 

 or perceptible sinuosity. This form differs from that figured by d'Orbigny, 

 and from the Montevideo shells examined, chiefly by having a longer spire 

 and shorter aperture, the latter half as long as the shell ; by having more 

 whorls, a smaller umbilicus, and by its somewhat greater size. 



Section PECTINIDENS n. sect. 

 LYMN^EA DIAPHANA King. 



(Plate XLVI, Figs. 3, 7, 9). 



Lymncza diaphana King, Zoological Journal, V, p. 344, No. 43, 1830. 

 Limncea diaphana King, Sowerby, Conchologia Iconica, XVIII, pi. 5, 

 fig. 30, 1872. 



