yfi Dentition of Pulmonate Molluahs. 



JLcploloiua. 



Only one species examined : — 



Leptuloma fuscocincta, Ad. Jamaica. 

 Jaw thin, arcuate, high, ends bluntly truncated; with perpendicular stria?; 



cutting edge with a median projection. 



Lingual membrane (PI. V, rig. I) as in Pkujioptycha. 



Acliatinella. 



In Annals of Lycenni of Xat. Hist, of New York, X, 331: 

 XI, 190, are given in detail my observations on the anatomy of 

 Acliatinella. I here give a summary only of what relates to the 

 jaw and lingual dentition. 



Most of the specimens examined were sent by Mr. Gulick. 

 A few were received from the Museum of Comparative Zoology. 



I have here grouped the species according to von Martens' 

 arrangement and snb-genera. I will state that, of Mr. G-ulick's 

 arrangement, the species examined represent the sub-genera — 

 Acliatinella, BuHmetta, Apex, Partulina, Auriculella, Laminella, 

 Amastra, Leptachatina, — all except Xewcombia: Carelia is treated 

 below. 



The result of my examination may be briefly stated, viz. : 

 that I find two types of dentition, one (a) including the species 

 of Partulina and Acliatinella, s. s. ; the second (b) comprising 

 all the species examined, of Newcombia, Laminella, Leptachatina. 



Bull nulla, Apex and Labiella, of von Martens' arrangement, 

 were not examined. Of these we may expect to find the first 

 two agreeing w T ith my first section (a) in dentition; the last, with 

 my second (b). 



In the section [a) suggested by me, the species are all charac- 

 terized by a jaw so extremely delicate as to be found with great 

 difficulty. It cannot be extracted by potash. It is arcuate, ex- 

 tremely thin, transparent, with blunt ends. The lingual mem- 

 brane agrees with that figured by Heynemann of A. bulimoides. 

 It is very broad in comparison to its length. In one lingual 

 there were 175-1-175 teeth. They are arranged en chevron. 

 There is but one form of tooth for centrals and side teeth (it is 

 difficult to call the latter laterals or marginals), but the centrals 

 are somewhat smaller and symmetrical. The base of attachment 



