NATURAL SCIENCES OF PHILADELPHIA. 



189 



P. Blandi, Hoppii, variolosa, decora, corpidenta, Rowelli, Cali- 

 fornia, modica, Arizonensis, hordeacea, armifera, borealis, con- 

 tracta, and pellucida, not examined. 



P. pentodon has 64 rows of 10 1 10 teeth, with 4 perfect late- 

 rals (fig. 30). 



P. corticaria has 1 2 1 12 teeth, with 3 perfect laterals (fig. 31). 



P. rupicola (pi. XV., 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. 



Fig. 32. 



$y : 



Jaw of Vertigo 

 ovata. [Mor.-e.] 



Fig. 33. 



Genus VEETIGO, Mull. 



Jaw more or less arched, ends but little attenuated, blunt: an- 

 terior surface with delicate vertical striae ; cutting margin with a 

 more or less developed median projection. 



1 have given figure 32 copied from that of Morse. 

 In the L. and Frw. Shells N. A., I., will be found 

 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. 



Figure 33 shows the gene- 

 ral arrangement 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 

 (I presume) a distinct 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 unsym metrical. 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 15 rows of 11 111 teeth, with 7 perfect laterals. V. Bolle- 



Lingual dentition of Vertigo ovata. [Morse.] 



