292 HELICINID A. 
ALCADIA, Gray. 
Distr.—28 sp. West Indies. 4. Browntt (Ixxvii, 39). 
Shell Helix-shaped, often velvety, callous beneath ; columella 
flattened, straight; peristome slit in front. Operculum shelly, 
semiovate, with a tooth-like process adapted to the slit in the 
peristome. 
LucIDELLA, Swainson. 
Distr.—5 sp. West Indies. JL. aureola, Fer. (1xxvii, 40). 
Shell depressed, heliciform, slightly callous at the base; aper- 
ture triangular, sinuous ; peristome thickened, with superior and 
inferior tooth-like internal laminz. Operculum membranous. 
Bourciera, Pfeiffer, 
Disir.—2 sp... Equador... B.. heliciniformis, ,Pir. (xxvii, 
41, 42). 
Shell heliciniform, subglobose; aperture oval; peristome ex- 
panded, produced at the base. Operculum paucispiral, corneous. 
Bourciera absorbs away the inner whorls of the shell, like 
Helicina; its dentition also agrees with that group. 
SroastoMa, C. B. Adams. 
Etym.—Stoa, pillared, stoma, mouth. 
Syn.—Hemicyclostoma, C. B. Ad. 
Distr.—83 sp. One in Isleof Opara, Philippines, one in Hayti; 
all the others in Jamaica. S. pisum, C. B. Ad. (1xxvii, 43). 
Shell minute, globose-conic or depressed, spirally striated ; 
aperture semioval ; peristome continuous ; inner margin straight, 
forming a small spiral keel round the umbilicus. Operculum 
shelly, lamellar. 
ELECTRINA, Gray. Shell smooth. S. succinea, Sowb. (Ixxvii, 
44), is the only species. 
WILKINSON/HA, Chitty, 1857. Shell subdiscoidal, spirally car- 
inated, last whorl much produced. 8S. Wilkinsoneanum, Chitty. 
FADYENIA, Chitty, 1857. Shell with the spire depressed, sub- 
angular on the upper part of the last whorl, subplanate at the 
periphery, subangulated below, and subplanate round the umbil- 
icus. S. Fadyenianum, C. B. Ad. 
METCALFEIA, Chitty, 1857. Shell depressed conic. S. Metcalfe- 
canum, Chitty. 
PETITIA, Chitty, 1857. Shell globose, discoid. 8S. Petitianum, 
C. B. Ad. 
LINDSLEYA, Chitty, 1857. Shell globose, conic. S. Lindsley- 
anum, ©. B. Ad. 
BLANDIA, Chitty, 1857. Shell subdiscoidal. S. Blandianum, 
C. B. Ad. 
LEWISIA, Chitty. Shell subdiscoidal; aperture semiovate ; 
peristome continuous, with a spiral callus at the base excessively 

