CONCHOLOGIA CESTRICA. 



53 



lip simple, with the margin thickened, and often rufous; 

 lingual membrane, with 90 rows of 43 teeth, each ; 

 buccal plate slightly arcuate, with conspicuous longi- 



Lingual Dentition of Z. lubricoidea. [Morse.] 

 Fig, 94, 



tudinal striae ; cutting edge with an obtuse beak in the 

 centre. H. 5, W. 2, mill. 



Station, under the bark of decayed timber, and moist 

 decayed leaves. Chester County ; frequent. 



OBS. This shell was, for a long time, supposed to 

 be identical with the English species, Zua lubrica, Miil- 

 ler. To this opinion, the late Dr. Stimpson was the first 

 to demur, on the score of its wide diffusion over this 

 Continent ; and a further examination, by Prof. E. S. 

 Morse, tends to confirm the suggestion of Dr. Stimpson, 

 as to its specific distinction. Fig. 95, a, represents an 

 enlarged view of the central and lateral denticle of Zua 

 lubricoidea, Stimp.; and Fig. 95, b, the same denticles 



t, Dentition of Z, lubricoidea. b, Dentition of Z. lubrica, [Morse.] 



Fig, 95, 



of Zua lubrica, Mull. Our shell also differs in other 

 respects from its foreign analogue. 



