228 PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 



1897 ^ quemadensis v. Ihering, in : Rev. Mus. Paul., v. 2, p. 304, pi. 3, f. 7. 

 1897 V- philippiana v. Ihering, ibid., p. 305 (non V. pliilippiana Dall., 1890). 

 1899 V. philippiana v. Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 34. 



1899 V. quemadensis v. Ihering, ibid., p. 34. 



1900 V. gracilior Ortmann, in: Amer. Journ. Sci., v. 10, p. 381. 



This species is extremely near the preceding, and it may be only a 

 variety of it. According to our material it differs in the following points: 



1. The shell is more elongated, and the whorls are higher. 



2. The longitudinal ribs are more numerous (about 18-20), and do not 

 end abruptly before reaching the suture; they disappear gradually, and 

 traces of them are continued to the suture. They do not form a series 

 of tuberculiform prominences. 



3. The whorls are more evenly convex, with hardly a trace of a shoulder. 

 The upper part of the whorls is only slightly depressed. 



4. There are, as a rule, only two columellar plaits, although traces of a 

 third (upper) one are sometimes developed. 



Meastirements : Height, 135 mm; diameter, 66 mm (large part of spire 

 missing). Height, 119 mm; diameter, 46 mm (not quite complete). 

 Height, 88 mm ; diameter, ca. 36 mm (only uppermost part of spire miss- 

 ing, but last whorl damaged). 



Remarks: I unite the two species called by v. Ihering V. philippiana 

 and V. qtiemadensis, respectively. V. philippiana is said to possess a 

 longer spire, and longitudinal ribs, which do not terminate in tubercles, 

 and the whorls are said to be evenly convex : in all other respects it 

 resembles V. triplicate. V. quemadensis is said to differ from V. pJiilip- 

 piana in the still more elongated spire, with higher whorls, the larger 

 number of ribs, and the presence of only two plaits on the columella. 



Among our material, I find that the external form is very variable. 

 Although all specimens registered under this form are more slender than 

 the average of V. triplicate, there are, among the latter, individuals which 

 approach this form closely. Those with the most slender spire, and with 

 the highest whorls (almost as high as broad), which would correspond, in 

 this respect, to V. quemadensis, possess a distinct third columellar plait, 

 thus uniting characters of V. quemadensis and philippiana; as to the 

 number of longitudinal ribs, there is so much variability, that it is impos- 

 sible to draw any line. Indeed, in the more elongated individuals, the 

 number of these ribs is larger than in the typical V. triplicata, but some 



