CONCHOLOGIA CESTRICA. 47 
Shell obtuse-conic, reddish brown; 5S. labyrinthica, 
F ; enlarged. 
whorls 6, heavily ribbed, above, more [B. & B.] 
smooth beneath; lip thickened, some- 
what reflected; base flattened; umbilicus 
small; aperture narrow-lunate, with three 
revolving lamina, on the parietal wall — 

Jaw of S. laby- 
one at the base; and two, far within the rinthica. 
5 wee [S [ Morse. } 
outer lip, near the base; lingual mem- Fig, 76. 
brane with 78 rows of 13-I-13 teeth, 6h a 
(——_\ 
each; buccal plate slightly arcuate, mi- 
nutely notched on the cutting edge. H. 2%, W. 2) 
mill. 
’ 
Lingual Dentition of S. labyrinthica.—| Morse. ] 
Fig. 77, 
Rin. 
") ANAL By. 
Ss eye ace wit 

Station, under the bark of decayed logs. Chester 
County ; frequent. 
Sub-genus HELICODISCUS, Morse, 1864. 
Animal of Helicodiscus lineata, enlarged.—{[Morse.] 

Shell minute, flat; whorls equally visible, above and 
below, with revolving striz; unicolored, whitish; one, 
or more, lamellar teeth, within the outer lip. 
