282 CYCLOSTOMID A. 
MEGALOMASTOMA, Guilding. 
Syn.—Lomastoma, Woodward. 
Distr.—29 sp. W. Indies, E. Indies, India, Madagascar, Mau- 
ritius. Fossil. HEocene—. Paris and Isle of Wight. MM. Antzl- 
larum, Sowb. (1xxv, 59). 
Shell oblong or pupa-shaped, scarcely perforated, aperture 
circular. Operculum thin, horny, many-whorled, flat. 
FARCIMEN, Troschel. Lip thickened. W. Indies. M. ventri- 
cosum, d’Orb. (Ixxv, 60). 
MEGALOMASTOMA, Guild. Lip rather thin. W. Indies. 
COPTOCHEILUS, Gould. Narrowly perforate; aperture slightly 
touching or not touching the body-whorl; peristome not thick- 
ened, more or less duplicate. E. Indies. Scarcely distinct 
from Megalomastoma (restricted). MZ. altwm,Sowb. Philippines. 
ToMocycLus, Crosse and Fischer. Shell perforate, turreted, 
truncate; aperture subcircular, small; peristome duplex, the 
inner margin direct, the outer margin widely expanded, excised 
above. Operculum with a median posterior rounded process, 
margins of the whorls sublamellate. Central America, Guat- 
emala. JM. simulacrum, Morel. (1xxv, 61). 
HainesiA, Pfeiffer, 1856. 
Syn.—Mascaria, Angas. 
Distr._-4 sp. Madagascar, Siam. H. Myersi, Haines. 
Shell oblong-turreted, whorls convex, without epidermis, re- 
sembling Megalomastoma. Operculum angular, paucispiral. 
DACRYSTOMA, Crosse and Fischer, 1871. Whorls flattened, 
with very thin, deciduous epidermis. H. arboreum, C. and F. 
Madagascar. 
DipLoMMATINA, Benson. 
Distr.—100 sp. India, East Indies, Australia, Polynesia. 
D. folliculus, Pfr. (xxv, 62, 63). 
Shell suboval, costulate, dextral or sinistral, thin, scarcely 
perforated ; aperture subcircular; peristome double, outer margin 
expanded. Operculum horny, multispiral. The eyes are situated 
on the hind-part of the tentacles, at their base, and are composed 
of two lobes, one lobe deeply seated in the tentacle and larger 
than the other lobe, which is a small black point coming to the 
surface on the outer side of the larger lobe. The generic name 
is derived from this peculiarity of the eyes. 
PAXILLUS, H. and A. Adams. Shell small, pupiform, sinistral, 
rimate; spire pointed ; aperture semiovate, ascending on the body- 
whorl; inner lip spreading, l-plaited, outer lip expanded, notched 
in front; umbilicus defined by a rib. D. rubicunda, Martens 
(xxv, 64). 
DIANCTA, Martens. Penultimate whorl constricted. D. con- 
stricta, Martens (1xxv, 65, 66). 
