158 PROCEEDINGS OF THE ACADEMY OP 



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 b}' 

 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 my 

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

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

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



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

 brane of G. bullata, Texasiana, decussata, or Vanuxemensis, 



B. Jaw present. 

 Family HELICID^E. 



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

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

 ninse, Helicinse, Orthalicinee, Succininse. The characteristic of 

 each will be given below. 



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

 Genus MACROCYCLIS, Beck, 



Jaw crescentic, ends sharply pointed, anterior surface striated ; 

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

 ined the jaw of 31. Vancouver ensis (see fig. 3, 

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



ranti, Voyana, and in the West Indian species, 

 31. Baudoni, 1 Petit, and 31. euspira, Pfr. 

 Vancouver ensis. 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 31. Vancouveren- 

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



1 See Am. Journ. Conch. VII. 175; Ann. Nat. Hist. N. Y., X. 305. 



