164 PROCEEDINGS OF THE ACADEMY OP 



more separated than in Helix, and the separate rows are more 

 widely removed the one from the other, especially near the outer 

 margin of the membrane. 



Though the simple aculeate form of marginals seems a generic 

 character in Zonites, we find the marginals bifid in Z.fulvus (pi. 

 XVII., fig. 5), and bifid or even trifid in Z. Gundlachi (pi. III., fig. 

 10), also for the first four marginals in milium. This character 

 reminds us of Vitrina (see belowj ; Vitrinoconus (Semper, Phil. 

 Archip., 91) ; Vitrinoidea (Ibid., p. 85) ; Vitrinojysis (Ibid., p. 86), 

 and the numerous genera of disintegrated Nanina ; also some 

 species of Limax. The first marginals of Z. exiguus have a side 

 spur. 



Taking the general characters of dentition into consideration 

 Zonites is nearest allied to Limax among our genera, but in the 

 latter the marginals are generally more slender "or spine-like, and 

 have a less sole-like base of attachment. 



The approximate count of teeth in the various species now 

 follows : 



Zonites capnodes (pi. III., fig. 12; pi. II., fig. 6) has 66 1 66 

 teeth, with 9 perfect laterals on each side the median row. An- 

 other specimen gave 46 1 46 teeth, with 70 rows of teeth in all. 



Z.fuliginosus (pi. II., fig. 7) gave 87 rows of 64 1 64 teeth. 

 Another specimen 57 1 57. Both linguals have 4 perfect laterals. 

 Fig. 6 gives the eighth marginal from the outer edge. 



Z. friabilis (pi. II., fig. 4) has 57 1 57 teeth with 6 laterals. 

 Fig. b gives the extreme marginals of two adjacent rows. 



Z. caducus 1 is known only by the description and figure of 

 Fischer and Crosse (Moll. Mex. et Guat. 149, pi. VIII., fig. 13-16). 

 There are 75 1 75 teeth with 5 laterals. 



Zonites Isevigatus (pi. II., fig. 1, 2) is peculiar in having no cut- 

 ting points to the side cusps of the central teeth, and no perfect 

 lateral teeth. I found in one specimen 28 rows of 19 1 19 teeth. 

 Another specimen had 17 1 17 teeth. One-half of one transverse 

 row with the central tooth is figured on pi. II., fig. 1. A more 

 enlarged view of a portion is given in fig. 2. 



1 I will here mention that Semper, Archip., Phil. 78, pi. III., fig. 27; 

 pi. V., fig. 21, figures the genitalia, jaw, and dentition of a Zonites from 

 Tennessee, which he refers to Z. lucubratiis, Say. I do not know what 

 species he had before him. Z. lucubratw is not found in Tennessee. See 

 Ann. K Y. Lye. N. H., pi. XL, fig. 24. 



