90 Dentition of Pulmonate Mollusks. 
Polymita muscarum, Lea. 
Jaw wide, low, arched, delicately striated; ends attenuated, bluntly 
rounded ; no anterior ribs; no median projection to the cutting edge. (PL 
OW, 1H, IE.) 
Lingual membrane long and narrow, composed of numerous rows of 
about 75-1-75 teeth each. The transverse rows are arranged en chevron. 
Centrals with base of attachment long, narrow, incurving at the sides; 
upper margin slightly rounded; lower margin trilobed and fringed; on the 
lower fourth of the base of attachment springs a. trilobed, gouge-shaped, 
cutting edge, broader than the base, and bearing three cusps, each produced 
into a cutting point, the central triangular, the external ones curving out- 
wards, neither produced beyond the lower margin of the base of attach- 
ment. ‘The side teeth (which do not resemble the usual form either of later- 
als or marginals) are of the same form as the centrals, but rendered asym- 
metrical by the lesser development of the inner lower angle of the base of 
attachment, and by its being thrown abruptly off towards the margin of the 
membrane; the lower edge is also rounded, and not trilobed as in the cen- 
trals; the laterals, also, are longer, narrower, with a less expanded upper 
margin of the base of attachment than in the centrals, in a contrary direc- 
tion from which they are also thrown off by the irregular curving of the 
base of attachment. The cusps and cutting points of the side teeth are like 
those of the centrals. 
In one lingual membrane examined, I noticed two abnormal rows of 
teeth down the whole length of the membrane, in which the cutting edge 
was divided into four lobes, instead of three, all bearing cutting points. 
These abnormal lines of teeth were separated by a normal line. 
The figure (Pl. ILI, fig. C) shows a group of central and side teeth, while 
a single central, still more enlarged, is shown in D: . 
These peculiar, long, subquadrangular bases of attachment, not reflected 
along the upper margin, as usual in the Helicidw, but bearing the gouge- 
shaped, expanded cutting edge, soldered as it were upon its surface, can 
only be compared to those of Gqotis, and those of the marginal teeth of 
Orthalicus and Liguus. 
Polymita picta, Born. Cuba. The specimen examined was 
found on a bunch of bananas in New York. 
Jaw as in MUSCATUIMN. 
Lingual membrane (PI. ILI, fig. E) with the same characteristics as that 
of muscarum; but the teeth are shorter and stouter. (Plate III, fig. E.) 
HEMITROCHUS. 
I have examined only five species of those remaining in von 
Martens’ Polymita, after removing its type, muscarwm, as eXx- 
plained above. Helix versicolor, Born, is the only remaining 
