EASTERN PROVINCE INTERIOR REGION SPECIES. 2j3 



striae. 1 have not found the striae as oblique as shown iu Fig. 265. 

 In soUtaria, alternata, and HemphiUi there are no traces of either ribs, 

 wrinkles, or striae. In all these species there is a tendency to a median 

 projection to the cutting edge. This is greatly developed in solitaria, 

 alternata, Cumber I andiana (with i^erpendicular striae), and especially in 

 HemphilU. The last two species have also a much more arcuate jaw 

 than the others. I have not seen the jaw of Horni or patqjer. 



Fig. 2G6 shows the general arrangement of the teeth on the mem- 

 brane. The characters of the individual teeth are better shown in Fig. 

 8, on p. 49. 



p. Cumberlandiana. 



There is a considerable difference in the lingual dentition of the 

 species I have grouped in this genus as to the development of the side 

 cusps to the central and lateral teeth, and the presence of distinct cut- 

 ting points upon these cusps. Such cusps and points are present in soU- 

 taria, alternata, perspectiva, striateUa, HemphiUi, Iclahoensis, asteriscus. 

 I do not detect these cusps in P. strigona, Coopcri (probably the same 

 species), or Cumherlandiana, excepting on the outer laterals. The central 

 and lateral teeth of all the species examined by me are in other respects 

 as usual in the Helcidw. It will be noticed that the base of attachment 

 is subquadrate, the reflected portion large (except iu asteriscus), the 

 cusps short, the cutting points short. All the outlines of the teeth are 

 less graceful than in Zoniles. The lateral teeth are made asymmetrical 

 by the suppression of the inner lower angle of the base of attachment, 

 and the less development, if not suppression, of the inner cusp, which 

 loses the cutting point also. The marginal teeth are quite different 

 from those of Zonites, Limax, Vitrina, Macrocyclis, and Glandina in not 

 being aculeate. They are more crowded than in those genera. They 

 have a quadrate base of attachment, not sole like, shortened on its 

 inner lower side, but produced at its outer lower margin. The reflected 

 portion is as wide as the base of attachment, is more produced than in 

 the central and lateral teeth, retains its width throughout, and bears 

 two oblique, blunt cutting points, the inner one always much the larger 

 and longer, and the outer one of which, in most of the s])cci( s. has a 

 tendency to bifurcation. There i.^ considerable variation in these cut-^ 



