ODONTOSTOMUS. 99 



mill, long, 121 to 13 wide, with 7 whorls, aperture lHx9 mill. It 

 is said by Doering to be the normal form, encountered in great 

 abundance in the Sierra de Cordova. According to Kobelt, who 

 received a specimen from Doering, it is 30 mill, long, like the type 

 in dentition of aperture or having two accessory folds between the 

 two basals ; whorls 7-7^. 



Var. minor Doer. (figs. 4, 5) is only 19-23^ mill, long, 101 wide, 

 and said to be somewhat more obese than the type, with typical teeth. 

 It seems to me to be an absolute synonym of typical dczdahus. It 

 occurs chiefly in the more sterile and dry localities, around the peaks 

 of the Sierra de Cordova. 



4 



Var. multidentatus Doering (pi. 14, fig. 9), predominates in dry 

 places in the pampas. It agrees with var. minor in the obese shape, 

 but the dentition is much stronger. Three strong cords run out from 

 the lamella on the parietal wall, two from that on the columella. 

 The first basal fold is doubled, and in place of the second there are 

 three parallel folds running into the transverse barrier, and even 

 visible upon it. There is another fold interposed below the large 

 lamella (upper palatal fold) of the outer lip, and the surface of the 

 large fold bears a strong ridge. The types measure, length 20, diam. 

 25, aperture 10x8 mill., whorls 6; and 25, 13, apert. llx'.i mill., 

 whorls 6. 



Var. strobeU Doering (1877). Shell elongate, with acutely conic 

 spire ; the columellar lamella usually has a little tooth about the mid- 

 dle of its base ; the secondary upper tooth of the parietal lamella is 

 usually less prominent. The largest specimens were collected on the 

 Cerro de Yerba Buena, in the Sierra de Aconjigasta, and measure : 

 Length 30, diam. 13, apert. 12 mill., whorls 7-1 ; length 33, diam. 14, 

 apert. 13 mill., whorls 7f. Further south a diminution in size is 

 observable. For example, a specimen from S. Javier measures : 26, 

 12, 11 mill., whorls 7. 



Var. salinicola Doering (1877). Of smaller size, and much less 

 striate. The secondary superior tooth of the parietal lamella is sep- 

 arated entirely from the principal by a space. Length 23-26, diam. 

 12-13 mill., whorls 7. From the saline margins of the Laguna de 

 Pocho. 



0. BRACKEBUSCHII Doering. PI. 14, figs. 10, 11, 12. 



Shell cylindrical, longitudinally striated, opaque, subcalcareous, 



