366 COSTIGO. 



dorsal side, turning downward at the inner end. The upper 

 palatal fold emerges to the lip where it terminates in a 

 rounded prominence. It penetrates very deeply, running ob- 

 liquely downward. The lower palatal, which is situated far 

 within, appears to consist of two rather short, oblique laminae 

 meeting below in form of a wide V. The lip is expanded, 

 thickened ; parietal callus strong. 



Mr. Smith's figure of the sinistral form referred to this 

 species, copied in fig. 13, shows the sinulus less enclosed than 

 in the dextral. In the typical form figured by Mr. Smith 

 (fig. 17) the upper part of the peristome is some distance 

 below the preceding suture. The external pit over the colu- 

 mellar lamella and lower palatal fold is broad and rather 

 deep. The length and diameter are given as equal by Mr. 

 Smith ; in one measured the length exceeds the diameter. 



Mutation ascendens, pi. 33, figs. 16, 18, 19. Suture of the 

 last whorl ascending to the preceding suture. Base more 

 swollen, the pit smaller. Length 1.5, diam. 1.6 mm. 



Mut. cantrarius, pi. 33, fig. 13. Shell sinistral. Known to 

 me by Mr. Smith's figure, here copied, which shows a less 

 completely enclosed sinulus. 



Genus COSTIGO Boettger. 



Costigo BTTG., Bericht Senck. naturf . Ges., 1891, p. 270, as 

 a section of Vertigo, for V. (c.) saparuana Bttg. 



"Differs from the section Alaea by the scarcely glossy 

 shell, densely striate or costulate, the neck simple, without 

 annular callus [crest], a single parietal tooth, no angular. 

 Columellar tooth always present; palatals to 2. Moluccas 

 and Philippines ' ' ( Bttg. ) . 



This group, which appears very nearly related to Neso- 

 pupa, is not known to us by specimens. To the species de- 

 scribed by Boettger are added a few Mascarene and African 

 forms which agree in teeth. It is probably not a natural group 

 in its present limits merely a convenience. 



1. COSTIGO SAPAEUANA (Boettger). PI. 31, fig. 12. 



Shell small, punctate-rimate, subacutely ovate, corneous- 



