NATURAL SCIENCES OF PHILADELPHIA. 175 



50 teeth, with 18 perfect laterals. The centrals have a much more 

 graceful outline to the reflection than in the two last-named 

 species. The median cusp is longer and more slender, with a more 

 slender cutting point ; the subobsolete side cusps are more marked, 

 and bear well developed, triangular, slightly curved cutting points. 

 The lateral teeth are like the centrals, but unsymmetrical by the 

 suppression of the inner lateral lower expansion of the base of 

 attachment. There is, however, an inner cutting point lying 

 against the inner side of the cusp, rather than in a position cor- 

 responding to the outer cutting point ; it is very difficult of de- 

 tection, being on a different plane from the outer cutting point, 

 and readily confounded with the inner lower angle of the base of 

 attachment. It is figured by Lehmann and Heynemann. The 

 marginals are long and slender, without bifurcation even on those 

 on the extreme edge of the membrane. Fig. 105 of p. 63 of L. 

 and Frw. Shells N. A. I., probably was drawn from a specimen 

 of this species, certainly not from one of flavus. 



Goldfuss (1. c. pi. V., fig. 4) omits the cutting points from his 

 figure. 



Limax Heivstoni, J. G. Cooper (pi. IV., fig. 2). The centrals 

 and laterals are of the same type as in the last species, witli this 

 important difference, that there is a well-developed cutting point 

 of the usual form (not the peculiar form as in L. agreslis) to the 

 inner subobsolete cusp of the laterals, and the inner lower lateral 

 expansion of the base of attachment of the laterals is not sup- 

 pressed as usual to make the laterals unsymmetrical. From this 

 it follows that the central teeth are with difficult}' distinguished 

 from the laterals, until the outer ones are reached, when the inner 

 cutting point and inner lower lateral expansion of the base of 

 attachment are suppressed as in the other species of Limax. The 

 marginal teeth are not bifid. Teeth 30 1 30, with 14 perfect 

 laterals. Fig. b represents the very last marginals. As in the 

 membranes of almost all species of land shells, there is consider- 

 able difference in the marginals on different portions of the same 

 membrane. Those figured are the least slender. 



This species, by the presence of the inner cutting point of the 

 laterals and non-bifurcation of the marginals, resembles Limax 

 (Amalia) gagates, as figured by Semper (Phil. Archip., pi. XI.), and 



nutkla Mollusker, pi. I., fig. 3), disagrees with my observation by the bifur- 

 cation of the marginals. 



