PILSBRY: non-marine MOLLUSCA of PATAGONIA. 54 1 



Arroyo Eke, near the headwaters of Spring Creek (north of the Rio 

 Belgrano), April lo, 1898. 



Except on the spire, the cuticle is generally well preserved. When 

 worn on the last whorl, it is deciduous along the spiral striae, which other- 

 wise are hardly noticeable. These shells are readily distinguishable from 

 any taken at lower levels, along the Rio Chico. 



Chilina campylaxis sp. nov. 



(Plate XLlUa, Figs. i-2a.) 



The shell is oval, much inflated, thin. Dead individuals, but evidently 

 almost or wholly unchanged in color, are light reddish-brown, with rather 

 faint streaks of chestnut, which are angular and dilated to form three bands 

 of sagittiform spots besides a row of small spots below the suture. These 

 markings are often less fully developed than in the figured specimens, and 

 they are generally removed in part by the erosion of the surface. Where 

 the cuticle is retained behind the outer lip, it is yellow. The surface 

 shows spiral striae more distinct than usual. The aperture is light brown 

 or fulvous inside. The outer lip does not seem to be thickened within, as 

 it is in C. f. oUgoptyx. The columella is narrow, deeply concave, and has 

 a small but distinct fold above (rarely subobsolete.) 



Figs. I, \a. Length 19, diam. 11. 2, length of aperture 13 mm. 



2, 2a. " 18.2 " 1 1 



18 " II 



12 



12.25 

 12.8 

 13 



13 

 12 



17 " 10.8 



17 " II 



17.2 "II 



17 " 10.2 



The numerous specimens vary but slightly in size or other features. 

 They have some resemblance to the Magellanic C. patagonica, which 

 however is figured as having a straight columella and a stronger colu- 

 mellar fold. 



All of the specimens are "dead" shells. At this spring C. fulgiirata 

 oligoptyx was also found, both alive and among the dead shells which 

 were preserved separately ; the larger individuals have the outer lip 

 noticeably thickened. The shells of C. campylaxis differ constantly from 

 the associated oligoptyx in various structural features, and must, I think, 

 be regarded as specifically diverse. 



