200 PROCEEDINGS OF THE ACADEMY OF 
The lingual membrane of obvoluta is described by Goldfuss 
(1. c. 45) with a type of central teeth differing from that I have 
shown in Yatesv. 
Subgenus STROBILA. 
Jaw low, wide, slightly arcuate, ends scarcely attenuated, blunt; 
cutting margin without median projection; anterior surface with 
(over 12 in labyrinthica, numerous in Hubbard?) crowded ribs, den- 
ticulating either margin, and more developed on the centre of 
the jaw. | 
Lingual membrane of labyrinthica long and narrow, with 78 
rows of 18—1—13 teeth each, with 5 perfect econo. Morse 
Fig. 44. 
Sara dentition of Helize aren Morse] 
figures 6 laterals. Centrals with a base of attachment about square, 
upper edge broadly reflected ; reflection very short, bearing along, 
slender, median cusp reaching the lower edge of the base of attach- 
ment, with a short cutting point extending slightly beyond it; 
side cusps very small, each bearing a short cutting point. Lateral 
teeth like the centrals, but unsymmetrical by the suppression of 
the inner lower angle of the base of attachment, and the inner side’ 
' cusp and side cutting point. Outer laterals gradually changing 
into the marginals, which are low, wide, with a reflection equalling 
the base of attachment, and furnished with numerous (about 5) 
subequal, short cutting points, the inner one longest and bifid 
(pl. XVIII, fig. 7). 
Morse mentions no ribs on the anterior surface of the jaw, but 
they are well developed on the specimen examined by me. 
Helix Hubbardi, a specimen from Bonaventure Cemetery near 
Savannah, kindly opened by Mr. Bland, furnished a jaw and lin- 
gual membrane. Jaw long, low, slightly arcuate, ends acuminated; 
no median projection to cutting edge; anterior surface with nu- 
merous crowded ribs, denticulating either margin. | 
