CHALKPOTAXIS. 



167 





S.gibboni Pfr., v, 182. 



magnified Lea not Fer. 



v. amori Hid., v, 183. 



v. cousini Jouss., v, 183. 

 S. pnestaiis Pfr., v, 184. 

 S. braziliaua Fer., v, 184. 



? moricandi Beck. 

 S. heliaca Orb., v, 135. 

 S. pascalia Caili., v, 186. 



amazonica Hupe. 

 S. amazonica Pfr., v, 186. 

 S. feistharneli Hupe, v, 187. 



pundata Wagn. not Miill. 



v. planior Pils., v, 188. 



S. incarum Phil., v, 192. 

 S. monile Brod., v, 192. 



planorbis Jay. 



boetzkest Mill. 

 S. castelneaudii D. & H. v, 193. 



castelnaudii Hupe. 



castelnaui Pfr. 

 S. selenostoma Pfr., v, 193. 



sclerostoma Rv. 

 S. hians Pfr., v, 194. 

 S. tiloriensis Aug., v, 194. 

 S. iris Mill., v, 195. 

 S. rugifera Dohrn.,v, 195. 

 S. elaps Dohrn v, 196. 



Genus CHALEPOTAXIS Ancey, 1889. 



Chalepotaxis Ancey, Conch. Exch. Aug. 1887, p. 22, type Nanina 

 f infantilis Gredl. Cf. SCHACKO, Jahrb. D. M. Ges. XI, p. 157, pi. 

 3, f. 7-10 (dentition). 



Shell small, thin, shining, orbiculate-depressed, with narrow um- 

 bilicus and low-conic spire ; last whorl scarcely descending in front 

 aperture lunate, slightly oblique, the peristome simple and unex- 

 panded except at the columella, where it is slightly dilated. Type 

 C. infantilis Gredler, pi. 57, fig. 34. 



Jaw very delicate. Radula (pi. 57, figs. 35-39, C. infantilis^with the 

 formula 25.1.25. Teeth all similar in form and in v-shaped rows. 

 Middle teeth having the median cusp enormously dilated into an 

 elliptical gouge projecting far beyond the basal- plate ; neck of the 

 cusp narrow, bottle-shaped ; side cusps basal, rudimentary and verti- 

 cal ; basal-plate narrow in front, widening and squared behind. 

 Lateral teeth similar, but the large cusp bends outward and the 

 entocone is suppressed. Marginals differ only in becoming smaller, 

 with the ectocone decidedly longer (pi. 57, figs. 35, 37, group of 

 middle and lateral teeth; fig. 36 group of marginals; fig. 38, a 

 lateral in profile, turned 90 ; fig. 39, a lateral turned 45). 



This genus is founded upon one species having a shell resembling 

 an immature H. similaris Fer., or pyrrhozona Phil, and a type of 

 dentition considerably like Oxychona. The jaw is very imperfectly 

 known, and the genital system is unobserved. I am disposed to 



