504 



MICHIGAN SURVEY, 1905. 



Family PUPILLID/C. 



Jaw smooth or finely striate, lower margin with or without a projection^, 

 sometimes reinforced with a superior arched appendage, like^ forming a. 

 double jaw, and to be compared to the accessory plate of the jaw of Suc- 

 cinea; lingual membrane similar to that of the Helicidce; central tooth of 

 same form and usually of same size as the laterals, laterals tricuspid; mar- 

 ginal teeth quadrate, ^\^de, low denticulated. 



Shell generally multispiral, elongated, conic or cylindrical; aperture small^ 

 often narrowed by internal teeth or lamellae. 



''As it is well known, most of the folds or teeth in the apertures of Pupa 

 {Pupilla) have definite positions, and the principal ones are homologous 

 throughout the group. 



We therefore offer below a revised terminology of the apertural armature 

 applicable to all Pupidce {Pupillidce), and requiring no especial reference to 

 a key, as the terms are to a large extent sub-explanatory. 



The plan is to call all projections upon the parietal wall and columella, 

 ''lamellae," those within the basal and outer walls of the aperture "phcae'^ 

 or folds. The nomenclature of particular folds is then as follows: 



Lamellae. 



Supracolumellar. 



Columellar. 



Subcolumellar. 



Superpa'.atal. 

 Upper palatal. 



'^y 1- : : Outer palatal. 



, " --Lower palatal. 

 ti- z _ _ r. - Infrapalatal. 



Fig. 115. Apertural lamellae and folds of Fupillidce. (Pilsbry.) 



"But few Pupidce {PupillidcB), have all the folds named, and some of them, 

 are rarely present in American species. The infra-parietal, supra and sub- 

 columellar lamellae and the infra-, inter- and supra-palatal folds are ' second- 

 ary' in nearly all groups, and often vary in the species. The others are- 

 more constant, and vary but little in position w^hen developed. The pari- 

 etal and columellar lamellae and the lower parietal fold, are at the angles of a 

 nearly equilateral triangle, when the said palatal is not deeply immersed.''* 



* Pilsbry, Proc. A. N. S. P. 1903, 582. 



