460 A MANUAL OF AMERICAN LAND SHELLS. 



Leidy's figure iu all respects, indeed, but the jiosition of the retractor 

 penis, ^Yhich Lehmaun places at the top of the penis sac. His figure 

 of the dentition offuscus is nearer mine of the Boston specimens than 

 is his of Jiortensis, though the transverse count of teeth is larger. Gold- 

 fuss's figure of the dentition of A. Jiortensis also {I. c, Plate V, Fig. 6) 

 differs from my figure in the same way, i. e., by the presence of an inner 

 side cusp and cutting point to the lateral teeth. Thus I find it impos- 

 sible to decide from the genitalia whether to refer our species to fuscus 

 or Jiortensis, though I incline to the former. From the dentition I 

 should assuredly adopt the former name also. 



The jaw of the Boston specimen (Fig. 501) is thick, arcuate, ends but 

 Fig. 501. little attenuated ; no median projection to the cut- 



ting edge ; anterior surface with 8 stout, separated, 

 unequal ribs, denticulatiug either margin. 



Lingual membrane (Terr. Moll., V, Plate V, Fig. 

 jawof^./».c«*. fj^ j^^g. ^jj^j narrow. Teeth about 31-1-31, with 



about 10 perfect laterals. Centrals with the base of attachment longer 

 than wide ; reflection half as long as the base of attachment, bearing one 

 long, stout cusp, extending to the lower margin of the base of attach- 

 ment, beyond which projects the stout cutting point ; side cusps dis- 

 tinct, but small, with distinct, small, stout cutting points. Laterals 

 like the centrals, but asymmetrical by the suppression of the inner, 

 lower, lateral expansion of the base of attachment and the inner side 

 cusp and cutting point. The marginals are low, wide, with one long, 

 bluntly pointed, oblique cutting point, bearing a subobsolete smaller 

 point low down upon its outer side. This subobsolete side cutting 

 point is on some of the marginals much more developed. 



From the above remarks it will be seen that in this genus, as in Umax, 

 Zonites, and others, the lateral teeth are either bicuspid or tricuspid. 

 The number of cusps does not seem a generic character. 



The internal calcareous grains which represent the shell are in some 

 species isolated, in others aggregated into a nearer resemblance to the 

 internal plate of Limax. On this distinction are based the subgenera 

 LocJiea and Prolepis. 



Subgenus PEOLEPIS, Moq.-Tand. 



Shield covering an imperfect, rugose, shell like plate, formed by the 

 aggregation of a certain number of calcareous granulations. 



