HELICIDA. oll 
Thysanota, Albers, 1860. Narrowly umbilicate, trochiform, 
thin; whorls 74, scarcely convex, base carinated, with rigid 
hairs; aperture angularly lunar; lip simple, acute ; columellar 
margin slightly expanded. H. Guerini, Pfr. 5 sp. India. 
Kaliella, Blanford, 1863. Uncharacterized. H. Barrak- 
porensis, Pfr. 3sp India. 
Videna, H. and A. Adams, 1852. (Discus, Albers, 1850.) 
Shell widely umbilicated, thin, discoidal, carinated at the 
periphery, flat or somewhat elevated above, convex below ; aper- 
ture subtriangular; peristome simple, sharp or slightly thickened. 
75 sp. Mostly Polynesian and Australasian. H. acutimargo, 
Pfr. Philippines (xciii, 5). 
Sitala, A. Ad., 1856. (Conulema, Stoliczka.) Shell conoid, 
thin, consisting of many whorls, usually spirally ribbed or 
striated; base convex, narrowly or indistinctly umbilicated ; 
margin of aperture thin, not expanded, outer margin simple. 
Animal narrow, long; gland at the end of the foot, beneath a 
distinct horn; two shell-lobes and two dorsal lobes on the 
mantle, all of them small and with no separately produced 
appendages; jaw thin, smooth, indistinctly concentrically 
striated in the middle. 7 sp. Southern Asia. H. aittegia, 
Benson. 
GLYPTOSTOMA, Bland and Binney, 1873. Shell widely umbili- 
cated, depressed, with wrinkle-like striz, solid; whorls six, the 
last depressed globose, not reflected at the aperture ; aperture 
oblique, subcireular ; peristome simple, acute, thickened within, 
its extremities approaching; columellar lip scarcely reflected. 
Jaw imbricated; no mucous pore, The animal a true Helix, 
although the shell has some resemblance to the Zonitidee. Z. 
Newberryanus, Binney (xciv, 14). California. , 
PHRIXGNATHUS, Hutton, 1883. Shell conical or turbinated, of 
five or six gradually increasing whorls; peristome thin, not 
reflected. Animal heliciform; mantle subcentral, reflected 
anteriorly over the shell; foot without locomotive disk, rounded 
posteriorly, without mucous gland. Jaw papillate, imbricately 
folded; teeth quadrate, the laterals bicuspid. H. marginata, 
Hutton. N. Zealand. 
caracoLus, Montfort, 1810. (Discodoma, Swn., 1840, Ser- 
pentulus, Klein, Adams, 1855.) Shell solid, orbicularly de- 
pressed, carinated, flattened at base, umbilicated or imperforate ; 
last whorl deflected at the aperture; aperture oblong, subangular, 
peristome thickened, reflected, widened below the columella, 
which extends to or covers the umbilicus. H. caracolla, Ver. 
(i, 16, sealariform). 16 sp. West Indies. 
Polydontes, Montfort, 1810. Imperforate, globosely depressed, 
or conoidally globose, solid, striate; spire hardly elevated, con- 
oidal, apex obtuse; whorls 5-54, slightly convex ; the last large, 
