1889.] NATURAL SCIENCES OF PHILADELPHIA. 279 



Zanzibar. I find that a number of species referred by authors to 

 Albers' group Pella belong to Zingis or its immediate neighborhood. 

 Pella of Albers, Pfeiffer, Tryon and others, is a heterogeneous group, 

 composed of widely dissimilar elements. It cannot be properly 

 characterized until the anatomy ofJP. bisculpta Benson, its type, is 

 known. Of its other species, II. rarvplicata Bens. 2 belongs to true 

 Helix; H. vemieosa Krauss, seems to be a Rhytida; H. knysna- 

 ensis Pfr. belongs to Aerope ; H. natalensis Pfr. and a number of 

 other species to Zingis. 



It is likely that Zingis will be found to contain a number of 

 African species usually referred to Vitrina, such as V. poppigi Mke., 

 cornea Pfr., natalensis Pfr., ruppeliana Pfr., transvaalensis Craven ; 

 as well as a portion of the forms included by authors in Pella. 



Ariophanta i Zingis) natalensis Pfr. (PL ix, figs, h, i.) 



The shells of my specimens correspond with Pfeiffer's figures and 

 description. 4 The shell is so fragile that I found it almost im- 

 possible to remove the animal (hardened in spirit) without breaking 

 it. The foot (pi. ix, fig. i) is rather narrow and long, the sole in- 

 distinctly longitudinally tripartite. Above its lateral margins are 

 well-defined longitudinal furrows. The mucous pore is subtriangular, 

 and there is a short horn above it. 



The radula (pi. ix. fig. h) has teeth of similar form to those figured 

 by von Martens for Zingis radiolata, so far as I can judge from his 

 figures, which do not show the form of the basal plates of the mar- 

 ginal teeth. The rhachidian plate has three cusps with strongly 

 reflected cutting-points. The lateral teeth are similar except that 

 the inner cusp is suppressed. They number nine on each side. 

 The transition to marginals is formed by the elevation of the outer 

 cusp upon the side of the principal one, as is usual throughout 

 Ariophanta , (' Nanina' ). The marginal teeth are very numerous, 

 close-set, and are all of the form shown in figure H, even to the tiny 

 outermost ones. 



1 Monatsb. K. p. Akad. Wissenschaften zu Berlin, 1878, p. 290 ; and Zooi. 

 Record, 1878, Moll , p. 63. 



2 Binney, Ann. N. Y. Acad. Sci., iii, p. 80. 



3 Binney, 1. c. p. 82. 



4 Monographia Heliceorum, i, p. 29; Conchylien Cabinet, Helix, pi. 29, 

 figs. 30-32. 



