122 GASTROCOPTA, AFRICA. 



extremely swollen median and upper whorls compared with 

 the lower ones. The obesity of the fourth whorl especially is 

 so pronounced that it appears larger than the following one. 

 This species, which I have not seen, is obviously related to 

 B. klunzingeri, which is from a higher, more humid region. 

 B. hcrmosa is smoother, and apparently wants upper palatal 

 and basal plicae, which are developed, but small, in B. klun- 

 zingeri, though reduced or wanting in the var. senegalensis. 

 Both are remarkable for the extreme convexity of the whorls. 

 Description and figure are from Jousseaume. 



68. GASTROCOPTA ACARUS (Benson). PI. 22, figs. 8, 10, 13. 



Shell rimate-perforate, cylindric-oval, very minute, cor- 

 neous, pellucid, the suture impressed, apex rather obtuse ; 

 whorls nearly 5, convex. Aperture rounded-ovate, 6-plicate: 

 one strong, lamelliform, irregular median parietal, 2 columel- 

 lar, of which the upper is minute, the lower strong and trans- 

 verse, and 3 short, not very deep palatal teeth, of which one 

 is basal and the next is larger. Peristome thin eorneous r 

 shortly, angularly expanded throughout, lightly margined 

 within. Length 1%, diam. % mm. (Bens.). 



Cape Verde Archipelago: S. Vicente, under stones (E. L. 

 Layard, type loc.) ; S. Antao, S. Vicente, S. Nicolao, S. lago 

 and Fogo, especially under the dead, loosened bark of Eu- 

 phorbias. 



Pupa acarus BENS., Ann. and Mag. of N. H. (2), xviii, 

 1856, p. 435. PPR., Monogr. Hel. Viv., iv, 686 (1859).- 

 DOHRN, Malak. Bl., xvi, 1869, p. 12. - - MORELET, Journ. de 

 Conchyl., xiii, 1873, p. 242. WOLLASTON, Testacea Atlantica, 

 1878, p. 515. Pupa acavus SCHAUFUSS, Paetel's Catal., 1869 y 

 p. 84. 



This species is thickly coated with dirt when alive. It is 

 much like G. damarica, which differs by having a low callous 

 on the columellar side of the angulo-parietal lamella, and a 

 slightly less thickened lip. The Antillean G. pellucida has 

 some forms extremely close to acarus, though perhaps not 

 absolutely identical. In my opinion, G. acarus is intermediate 

 between pellucida and the simpler of the forms I have de- 



