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Dentition of Pulmonate Mollusks. 89 
Patuia. 
Patula Huahinensis, Pfr. Huahine Island. Mr. A. Garrett. 
Jaw not examined. 
Lingual membrane with 18-1-18 teeth, of which about six on each side 
are laterals. The type of dentition is about the same as in Hndodonta incerla, 
described above. The marginals are, however, different, the two cutting 
points being bifid, the base of attachment low and wide. (Plate II, fig. L.) 
Pella. 
The character of the jaw does not allow the genus to hold a 
position here, among ‘‘ribless jaws.” 
Pella raviplicata, Benson. Cape Town, 8. Africa. Mr. J.S. 
| Gibbons. 
' The jaw has flat, crowded, numerous ribs, such as I have described for 
Microphysa Lansingi, in Terr. Moll., V. 
Lingual membrane (PI. III, fig. I) long and narrow. About 16-1-16 teeth, 
with four laterals on each side of the central tooth. The central tooth has 
small side cusps and cutting points. Laterals like the centrals, but slightly 
asymmetrical by the lesser development of the inner side; an unusual arrange- 
ment in the Helicide. The marginals are low, wide, with one inner, wide, 
bifid cutting point, and one smaller, bifid outer cutting point, giving a 
serrated appearance to the cutting edge. 
A central tooth, with its adjacent laterals, and two marginal teeth, are 
_ given in the figure. 
Polymita. 
Having found two different forms of dentition in the species 
referred by Von Martens to Polymita, I propose to restrict this 
+ genus to those species which have the abnormal dentition of its 
type, P. muscarum, leaving those with the usual dentition of 
the Helicid@ under the name of Hemitrochus. 
The peculiar dentition of Polymita, entirely unexpected from 
the appearance of the shell, is one of the most interesting facts 
Thave met with. It is not only different from that of its allied 
forms, but also from that of all species of the Pfeifferian genus 
Helix as yet examined. 
The peculiar dentition is shared by picta, Born, and may be 
‘looked for in sulphurosa, Morelet. These two species are placed 
by von Martens, in Ziochila, together with Helix Jamaicensis. 
Lhe two former I put with muscarwm in Polymita. For the 
last, see below. 
