158 PROCEEDINGS OP THE ACADEMY OF 



above, gives a better illustration of this central tooth than is 

 shown in my plate. I have lately verified it in fine specimens col- 

 lected by myself in Florida. 



In illustrating the dentition of this genus, I have given fig. 1, 

 copied from Dr. Leidy's figure in Terr. Moll. U. S., to show the 

 general arrangement en chevron of the rows of teeth. Fig. 2 by 

 Morse, copied from L. and Frw. Sh. N. A., I., gives one-half of 

 one transverse row of teeth, with the central tooth. Fig. 1 of ray 

 plate is intended to show the shape of the individual teetli : a gives 

 the central with adjacent marginals ; b, the twentieth marginal in 

 profile; c, the thirty-second and last marginal. 



I have not had an opportunity of examining the lingual mem- 

 brane of G. buUata, Texasiana, deciissata, or Vanuxemensis. 



B. Jatv present. 



Family HELICID^. 



This family may be divided by the character of its jaw in con- 

 nection with that of its dentition into several subfamilies, Vitri- 

 ninse, Helicinae, Orlhalicinse^ Succininse. The characteristic of 

 each will be given below. 



a. Jaw in one single piece ; marginal teeth aculeate. Vitrinin^. 

 Genus MACROCYCLIS, Beck. 



Jaw ci'escentic, ends sharply pointed, anterior surface striated; 

 cutting margin smooth, with a median projection. I have exam- 

 ined the jaw of 31. Vayicouverensis (see fig. 3, 

 Fig. 3. copied from L. and Frw. Sh., I.), concava, Du- 



ranti, Voyana^ and in the West Indian species, 

 M. Baiidoni,^ Petit, and M. euspira, Pfr. 



Jaw of Macrocyclis /. i ■ i 



vancouverensis. The general arrangement of the lingual mem- 



brane of Macrocyclis is the same as I have de- 

 scribed above for Glandina. 



There are 32 rows in one lingual examined of M. Vancouveren- 

 sis. The rows of teeth are arranged en chevron. Each row is 



' See Am. Jouru. Conch. VII. 175; Ann. Nat. Hist. N. Y., X. 305. 



