NATURAL SCIENCES OF PHILADELPHIA. 189 
P. Blandi, Hoppii, variolosa, decora, corpulenta, Rowelli, Cali- 
fornica, modica, Arizonensis, hordeacea, armifera, borealis, con- 
tracta, and pellucida, not examined. 
P. pentodon has 64 rows of 10—1—10 teeth, with 4 perfeet late- 
rals (fig. 30). 
P. corticaria has 12—-1—12 teeth, with 3 perfect laterals (fig. 31). 
P. rupicola (pl. X-V., fig. 2) has 11—1—11 teeth, with 5 perfect 
laterals. 
P. fallax (pi. XV., fig. 12) has 15—1—15, with 7 perfect laterals. 
Genus VERTIGO, Miill. 
Jaw more or less arched, ends but little attennated, blunt: an- 
terior surface with delicate vertical strize; cutting margin with a 
more or less developed median projection. 
I have given figure 32 copied from that of Morse. 
Hig. 32. In the L. and Frw. Shells N.A., I., will be found 
wl ay S other figures of jaws showing the variations in 
outline found in the genus. I have personally ex- 
amined the jaw in none of our species. 
For the characters of the lingual dentition 
I am also entirely dependent on Morse. 
Jaw of Vertigo 
ovata. {Morse.] 
Figure 33 shows the gene- 
ralarrangement of the teeth 
on the membrane. The 
membrane is long and nar- 
row. ‘The central teeth 
have a base of attachment 
higher than wide, subrec- 
tangular. The whole upper 
margin is broadly reflected. The reflection is very short, and bears 
three short stout cusps, the central the longest, each cusp bearing 
(1 presume) a distinet cutting point. The central tooth, in those 
species whose dentition is known to me, is as large as the laterals, 
and not smaller, as seems to be the rule in our species of Pupa. 
The lateral teeth are like the centrals, but unsymmetrical. The 
reflected portion is small, tricuspid or bicuspid. The marginals 
are wide, low, with a broad, irregular, denticulated reflection. Mr. 
Morse gives the following count of the teeth. V. Gouldi (fig. 34) 
has 75 rows of 11—1—11 teeth, with 7 perfect laterals. V. Bolle- 
ae 33. 
Lingual dentition of restaeie ovata. (Morse. ] 
