272 PROCEEDINGS OF THE ACADEMY OF [1898. 



b l . Inner lateral tooth with no ectocone ; that of the 

 outer lateral without cutting point. Species all Ja- 

 maican, 

 c. Axis slender, straight ; last whorl of shell be- 

 coming free, and keeled below ; aperture subcir- 

 cular, angular below, as wide as high. 

 d. Shell small, narrowly fusiform, with strong- 

 ly ribbed whorls. Section Geoscala P. & V. 

 d 1 . Shell slender, pillar-like, white and smooth, 

 of many narrow whorls. 



Section Mychostoma Alb. 

 c 1 . Axis a mere edge of contact between whorls ; 

 shell white, sinistral, slender, of many oblique 

 whorls, the last not free; aperture oval, longer 

 than wide. Section Apovia Beck. 



II. Axis of the shell a hollow column ; radula of normal form and 

 arrangement; central teeth tricuspid, short and wide; laterals 

 numerous, similar, bicuspid ; marginals wide, very short, multi- 

 cuspid (PI. XVII, fig. 2). 

 a. Shell very slender and elongate, thin, not conspicuously 

 calcareous, the axis subcylindrical or bulging in each 

 whorl, usually rugose. Genus EPIROBIA S. & P. 



a 1 . Shell stout, pupiform, with entire spire, conspicuously cal- 

 careous, etc., etc. Genus HOLOSPIRA Mart. 



III. CLASSIFIED LISTS OF SPECIES. 



As the groups defined by us in the preceding table of classification 

 differ radically in limits from those hitherto accepted, it is necessary 

 to supplement the characterization of the genera and subgenera by 

 detailed lists of species. These lists contain only species whose 

 characters we have ascertained by the examination of sections. 

 Those we have not been able to examine are omitted, 4 although a 

 large part of them could doubtless be approximately grouped by the 

 published information. 



The names of species of which the radula is known are distin- 

 guished by the following symbols : " (C F) " after the name of a 

 species indicates that the dentition has been examined by Crosse & 



4 The lists are, therefore, a catalogue of the species in the collection of the 

 Academy, excluding a considerable number of doubtful, unidentified or new 

 species. Any forms not mentioned herein we will be glad to receive and offer 

 an exchange for. 



