1898.] NATURAL SCIENCES OF PHILADELPHIA. 271 



which is cut into teeth or crenulated, at least in the 

 earlier whorls. Subgenus Gongylostoma Alb. 



c. Three to seven spiral laminae developed, increas- 

 ing in size from the upper to the lowest one, 

 which is largest. Section Pycnoptychia P. & V. 

 c 1 . Three laminae, the lowest smallest, upper largest. 



Section Callonia C. & F. 

 c 2 . Two subequal spirals; a median whorl with 

 accessory laminae upon the upper and basal 

 walls. Section Sectilumen P. & V. 



e 3 . Two spirals, the lower dentate in upper whorls, 

 and in an intermediate whorl expanding into a 

 very broad, flat or cup-like plate. 



Section Esochara P. & V. 



e*. Two gradually increasing spirals, the lower cren- 



ulate or denticulate ; sometimes a short, low, 



third spiral interposed in an intermediate whorl. 



Section Gongylostoma s. sir. 

 c 5 . Two strong, subequal spirals, both crenulated or 

 denticulate (Haiti). 



Section Amphicosmia P. & V. 

 e 6 . One incised or denticulate lower lamina with 

 sometimes a smaller one above it. 



Section Tomelasmus P. & V. 

 a 1 . Radula with the posterior cusp (ectocone) sub-obsolete or 

 wanting on the first or both lateral teeth ; two laterals on 

 each side enormously developed, the marginals abruptly 

 smaller, narrow, probably functionless, with vestigial cusps ; 

 arranged in horizontal lines (PI. XVII fig. 4). Axis of 

 the shell without laminae. 



Genus BRACHYPODELLA Beck. 

 b. Inner lateral tooth with a vestigial posterior cusp (ecto- 

 cone) without cutting point ; outer lateral with cut- 

 ting point developed on the ectocone. 



Subgenus Brachypodella. 

 c. Axis slender throughout, rarely with a small 

 spiral fold ; shell slender and elongate. 



Section Brachypodella s. str. 

 c 1 . Axis strong, heavily calloused ; shell obese. 



Section Strophina Morch. 



