22 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
A sliorter shell than the last with about 8 slowly increas- 
ing narrow whorls and an obtuse apex. 
It iS found with the two last. It occurs also in Vene- 
zuela and certain of tho Antilles. 
Height 10 mill., diameter 2£ mill. 
Oylixdrella Pfoitfor 1840. 
. Terrestrial Inoperculata with cylindrical shells generally 
striate or costate-striate and having a . truncato apex and a 
subcircular aperture without teeth or plaits. 
Cylindrella trinitaria Pfeiffer. 
A slender cylindrical turreted costulate-striate dark- 
brown shell with about fifteen whorls, tho last one partly 
froo and produced in front beyond tho othors ; a truncate 
apex, and a subquadrate aperture with an expanded peris- 
tome. It is found on the Laventille Hills. 
Height 11 mill., diameter 2£ mill. 
Ennea II. & A. Adams 1855. 
Terrestrial Inoperculata with shining cylindrical shells 
having an obtuse apex, a crenulate suturo and a thickened 
peristome with teeth and a strong parietal fold. 
Tho Molluscs classed in this and the next group aro 
united by some authors with tho genus Piqia, characterised 
as having shells generally of a cylindrical shapo with many 
slowly increasing whorls ; the last whorl is often no larger 
than the preceding or oven tho two or threo precoding ones, 
and tho apex is generally obtuso owing to tho increase of 
tho whorls being much greater at first than afterwards. 
The assemblage of species thus distinguished aro usually 
separated into subgenera ; and tho differences in the lin- 
gual dentition inclino mo to tho boliof that tho two groups 
of JSnnea and Vertigo , each represented by ono species in 
Trinidad, have claims to generic rank. 
