ALCADIA. 411 
13. A. mezgzastoma Adams. 
T. depresso-globosa, (sub epidermide fasciatim interrupta 
velutina) laevigata, nitüda, fuscula; spira depresso - conoidea; 
anfr. 4'/, parum convexi, ultimus magnus, basi convexus; 
apertura parum obliqua, semicircularis; columella breviter re- 
cedens, desinens in tuberculum exiguum, incisura levi a peri- 
stomate separatum ; callus basalis tenuis; perist. subincrassatum, 
"breviter expansum, album. — Opere. solidiusculum, pallidum. 
— Diam. maj. 8, min. 6'/, alt. 5 mill. (Coll. Nr. 85.) 
Helicina megastoma Adams Contrib. to Conch. N, 1. p. 14. *) 
8. Testa tenuiore, pellucida, epidermide distinctiore: 
Helicina affinis 4dams in Proc. Bost. Soc. II. 1846. p. 102. **) 
Habitat in insula Jamaica. 
11. A. manecilemím Sdamsms. 
T. depressa, subdiscoidea, tenuis, subtüilissime punctulato- 
striata, pallide fuseula; spira parum elevata, vix acuminata; 
anfr. 4'/, 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. ('/,, min. 6, alt. 33/, mill. (Mus. Cuming.) 
Helicina macilenta Adams Contrib. to Conch. N. 1. p. 13. ***) 
Habitat in insula Jamaica. 
yellowish-white: with 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; labrum mode- 
rately reflected and thickened. Mean divergence about 1209; height 0,2; 
greatest breadth 0,285; least breadth 0,24 inch. — Var. inéermedia :. with 
a very small, but distinct obtuse notch; the spire is less elevated, and the 
shell is larger and thinner.  lIt is intermediate between the type of the 
species and 7. solifaria. Heigth 0,24; greatest breadth 0,34; least breadth 
0,29 inch. (Adams l. e.) 
*) 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 thiekened; 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 l.c.) 
**) H. soliariae nob. affinis, sed testa spira conica haud convexa, 
instructa; labro reflexo, infra angulato, haud scisso. — Jamaica. (Adams l. c.) 
***) Shell rather small and thin, subdiscoidal, flattened beneath; pale 
724 
725 
