346 OBELISCUS. 



Mexican Species. 

 11. C. TAMPICOENSIS (Pilsbry). PI. 20, fig. 1. 



See p. 24, where this species was described as a doubtful 

 Spiraxis. It is apparently nearest to the Spanish C. letour- 

 neuxiana, but differs from that by the distinctly though nar- 

 rowly expanded peristome (that of letourneuxiana being said 

 bo be simple and unexpanded in specimens a little larger than 

 tampicoensis) . The expansion of the lip leaves, with subse- 

 quent growth, one or two narrow varices on the last whorl, 

 in the largest shells. 



The question of whether this Mexican species is an importa- 

 tion from Spain, or is really indigenous, awaits the actual 

 comparison of specimens. It is now abundant in the drift 

 debris of the Panuco river, together with many small native 

 species. 



APPENDIX TO ACHATINIDJS. 



Genus OBELISCUS Beck. 



The following species should be inserted in Vol. XVIII, 

 p. 271, before Pseudobalea. 



Subgenus DOLICHOLESTES Pilsbry. 



Dolicholestes PILS., Man. of Conch, xviii, p. 266, for Acha- 

 tina dunkeri Pfr. (Oct. 2, 1906). 



Shell imperforate, narrowly turrite, smooth and glossy, 

 without varix-lines, composed of 9 or 10 nearly flat whorls. 

 Summit obtuse, rounded and smooth. Aperture small, 

 columella spirally twisted, prominent in the middle, the edge 

 excised or concave above and below the prominence. In- 

 ternal axis very slender and straight in the earlier whorls, 

 slightly sinuous in the penult and strongly so in the last 

 whorl. 



Reproduction viviparous, the embryonic shell smooth, 

 glossy, with round summit and 2% whorls, the columella ex- 

 cised below, similar to that of the adult form. 



