216 



PROCEEDINGS OF THE ACADEMY OF 



H.fidelis (pi. XIII., fig. 8) has 48148 teeth, with 15 perfect 

 laterals. The first marginal is shown in b, an outer marginal in e. 

 Usually the first marginals have a side cutting point. 



H. infumata (pi. XIII., fig. 9) has 45 1 45 teeth, with 16 late- 

 rals. Fig. b is the 17th tooth, from a different portion of the 

 membrane from c, which is the 20th; they show variation in the 

 transition teeth as to the presence of the side cutting point. Ex- 

 treme marginals are shown in d. 



Of the dentition of the other species of Aglaja foreign to our 

 limits but little is known. H. Ghiesbreghti (see Moll. Mex. et 

 Guat.) has very dissimilar teeth, especially the marginals. H. semi- 

 clausa (Malak. Blak. XV., pi. IV., fig. 4) also diners in its denti- 

 tion. The jaws of these species agree with those of infumata and 

 fidelis. 



Fig. 59. 



Subgenus Akionta. 



Jaw thick, high, arched, ends but little attenuated, blunt ; cut- 

 ting margin without median projection ; anterior surface with a 



few, separated, stout ribs, deeply denticulating 

 either margin, and so disposed as to leave 

 each end of the jaw free from ribs. I have 

 counted 6 ribs on the jaw of arrosa; 9 in 

 Townsendiana ; 6 in tudiculata ; 6 in Nickli- 

 niana ; 6 in redimita ; 6 in exarata ; 5 in Dia- 

 bloensis ; about *7 in Carpenteri ; 3 in ramentosa ; 5 in Calif omi- 

 ensis ; 4-6 in sequoicola ; 8 in Traski ; 8 in facta ; 6 in Kelletti ; 

 9 of unequal size in Stearnsiana. The jaw of ruficincta differs 

 in having over 10 ribs covering its whole surface, and in being 

 only slightly arcuate. 



J aw of Helix arrosa. 



Lingual dentition of Helix facta. 



I have not examined the following species : inter cisa, Mormo- 

 num, Duprt/tJiouarsi, Gabbi. 

 The subgenus is almost exclusively confined to our limits. There 



