NATURAL SCIENCES OF PHILADELPHIA. 165 
4. demissus (pl. III., fig. 6, 6 is the 15th tooth) has 45—1—45 
teeth, with 15 laterals. My specimen was one of the large Hast 
Tennessee form, called 7. acerrus by Dr. Lewis. The typical form 
from near Mobile has, however, a perfectly similar dentition. 
Z. ligerus (pl. III., fig. 11,5 is the 18th tooth ; c, a profile of one 
nearer the central line). Teeth 38—1—38 with 14 laterals. 
4. ntertextus (pl. III., fig. 8, 6 is from near the outer margin). 
I find difficulty in counting the teeth on one specimen examined 
by me, but I believe there are 61—1—61. There are 12 perfect 
laterals. Another specimen has 55—1—55 with 12 laterals 
Z. subplanus, not examined. 
4. inornatus (pl. II., fig. 5, fig. 6 is the 21st tooth). One spe- 
cimen had 87 rows of 23—1—23 teeth. Another had 26—1—26. 
Both had only two perfect laterals. 
4. sculptilis (pl. I1I., fig. 2, b are extreme marginals) 40—1—40 
teeth with 4 perfect laterals. 
4. Kiliotti (pl. III., fig. 5, 6 an extreme marginal) 32—1—32 
teeth with 6 perfect laterals. 
4. cerinoideus, not examined. 
Z. cellarius (pl. II., fig. 2, one-half of one transverse line with 
the median tooth) 14—1—14 teeth. There can hardly be said to 
be one perfect lateral. For the other abnormal characters of this 
lingual membrane see p. 163. The figures of dentition of the 
foreign form (by Lehmann, Lindstrom, etc.) agree with mine. 
4. Whitney2, not examined. 
4. nitidus. See Lehmann, Lebenden Schnecken, ete. p. 72, pl. 
X., fig. 23, for description and figure of the Huropean form. Ina 
specimen from Baldwin County, Alabama, furnished by Dr. E. R. 
Showalter, I find 25—1—25 teeth with 5 laterals—(pl. XVIL., fig. 
1, b is an extreme marginal.) Lehmann gives 28—1—28. 
The specimen examined had the dart-sac and dart described in 
the European form. | 
4. arboreus. Morse gives 82 rows of 21—1—21 teeth each. 
My specimen (pl. XVII., fig. 4, 6 is an extreme marginal) has 
about 16—1—16 with 5 perfect laterals. There are distinct side 
cusps as well as cutting points to the central and lateral teeth. 
4. viridulus (pl. XVII., fig. 6). Morse gives 54 rows of 
2(—1—27 teeth each. I have figured the central and first lateral, 
with one extreme marginal tooth, drawn from a specimen furnished — 
me by Mr. Allen of Orono, Maine. I find three lateral teeth. 
