200 PROCEEDINGS OF THE ACADEMY OF 



The lingual membrane of obvoluta is described by Goldfnss 

 (I. c. 45) with a type of central teeth differing from that I have 

 shown in Yatesi. 



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 Hubbardi) 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 13 1 13 teeth each, with 5 perfect laterals. Morse 



Fig. 44. 



a^eaa 



^t^^^ 033 ^^ C3 



Lingual dentition of Helix labyrinthica. [Morse.] 



figures 6 laterals. Centrals with a base of attachment about square, 

 upper edge broadly reflected ; reflection very short, bearing a long, 

 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 

 (pi. XVIII, fig. 7). 



Morse mentions no ribs on the anterior surface of the jaw, but 

 they are well developed on the specimen examined b} 7 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. 



