208 PROCEEDINGS OF THE ACADEMY OF 
quite blunt. Other portions of the membrane would furnish much 
more sharply pointed teeth. 
Hi. uppressa (pl. X., fig. 7) has 383 —1—33 teeth; about 12 perfect 
laterals. 
H. in flecta (pl. X., fig. 4) has 22-122 teeth ; 7 perfect laterals. 
This and the following species have inner marginal teeth with 
simple, not bifid, cutting points (c). 
H. Rugeli (pl. X., fig. 3) has 21—1—21 teeth ; 6 perfect laterals. 
H. tridentata (pl. X., fig. 1) has 25—1—25 teeth; 10 perfect 
laterals. The inner cutting point is bifid after the 10th. 
H. Mullant. The species is probably identical with devia. 
H. Har fordiana has 26—1—26, with 12 laterals. Jaw with over 
12 ribs. Received too late for illustration. | 
Hi. fallax (pl. X., fig. 5) has about 40—1—40 teeth; 14 laterals. 
This (not tridentata) had no bifurcation to the inner cutting point 
of the transition teeth, at least on the portion of the membrane 
examined by me. 
. H. introferens not examined by me. | 
_ H. Hopetonensis (pl. X., fig. 6) has 27—1—27 teeth as far as I 
can judge from an imperfect membrane. There are 7 perfect 
laterals. 
H. vultuosa not examined. 
H.. loricata (pl. XVIILI., fig. 4) has over 20190. teeth ; 8 
perfect laterals. 
Helix personata is the only European species of this subgenus, 
but no figure of its dentition has been published to compare with 
that of our species. The same is true of the two Central American 
species known. 
Subgenus MEsopon. 
Jaw stout, high, arcuate, wide, ends but little attenuated, blunt; 
no median projection to the cutting margin; anterior surface with 
numerous, separated, decided ribs, 
denticulating either margin. I have 
counted 13 in H. major; 10 in albola- 
bris ; 10 in multilineata; 11 in Pennsyl- 
vanica; 12 in Mitchelliana ; 12 in 
elevata; 13 in Clarki; 13 in exoleta; 
Jaw of Helix Sayii. [Morse ] 18 in Wetherbyi: 14 in dentifera ; 
