ALCADIA. 
411 
IB. A. megastoma Adams. 724 
T. depresso-globosa, (sub epidermide fasciatim interrupta 
velutina) laevigata, nitida, fuscula; spira depresso- conoidea; 
anfr. 4y a parum convexi, ultimus magnus, basi convexus; 
apertura parum obliqua, semicircularis; columella bre viter re- 
cedens, desinens in tuberculum exiguum, incisura levi a peri- 
stomate separatum; callus basalis tenuis; perist. subincrassatum, 
breviter expansum, album. — Operc. solidiusculum, pallidum. 
— Diam. maj. 8, min. 6'/ 2 , alt. 5 mill. (Coll. Nr. 85.) 
Helicina mcgastoma Adams Contrib. to Conch. N. 1. p. 14. * *) 
/?. Testa tenuiore, pellucida, epidermide distinctiore : 
Helicina affinis Adams in Proc. Bost. Soc. II. 1846. p. 102. **) 
Habitat in insula Jamaica. 
14. A. maeiSesita Adams. 725 
T. depressa, subdiscoidea, tenuis, subtilissime punctulato- 
striata, pallide fuscula; spira parum elevata, vix acuminata; 
anfr. 4 l / 2 vix convexiusculi, ultimus latior, basi planiusculus ; 
apertura diagonalis, subsemicircularis ; columella brevis, in 
denticulum antrorsum curvatum, extus incrassatum desinens, 
fissura angusta, profunda, arcuata a perist. simplice, breviter 
expanso separata; callus basalis tenuis. — Operc.? — Diam. 
maj. 7'/ s , min. 6, alt. 3% mill. (Mus. Cuming.) 
Helicina macilenta Adams Contrib. to Conch. N. 1. p. 13. ***) 
Habitat in insula Jamaica. 
yellowish-white : w r ith excessively fine striae of growth, and very lightly im- 
pressed microscopic spiral striae : apex subacute : spire well elevated , with 
the outlines rather convex: whorls four and one -half, rather convex, with 
a well impressed suture : aperture rather large, semicircular, with the notch 
at the base of the columella scarcely perceptible or wanting; lab rum mode- 
rately reflected and thickened. Mean divergence about 120°; height 0,2; 
greatest breadth 0,285; least breadth 0,24 inch. — Yar. intermedia: with 
a very small, but distinct obtuse notch; the spire is less elevated, and the 
shell is larger and thinner. It is intermediate between the type of the 
species and H. solitaria. Heigth 0,24 ; greatest breadth 0,34 ; least breadth 
0,29 inch. (Adams 1. c.) 
*) Shell globose conic, smooth and shining, rather thick, yellowish 
brown; spire with very convex outlines; whorls four and one -half, a little 
flattened ; last whorl very large and high , with corresponding size of the 
aperture, which is quite exactly semicircular; labrum moderately reflected 
and thickened ; columella and adjacent part of the last whorl bent into the 
plane of the aperture ; the columella is produced into a very minute tubercle. 
— Mean divergence 108°; length 0,2; greatest breadth 0,33; least breadth 
0,25 inch. (Adams 1. c.) 
**) //. solitariue nob. affinis, sed testa spira conica haud convexa, 
instructa; labro reflexo, infra angulato, haud scisso. — Jamaica. (Adams 1. c.) 
***) Shell rather small and thin , subdiscoidal , flattened beneath ; pale 
