CNGCAL OFS OMe Ae. 
Prate I. 
Genus CYCLOSTOMA, Lamarck. 
Testa globoso-turbinata vel conica vel cylindraceo-oblonga, 
varie umbilicata, nunc levigata, nune dense scabroso- 
decussata, anfractibus plerumque rotundatis ; apertura 
eirculari vel pyriformi-circulari, labro reflexo, raro 
simplici, interdum fimbriato. Operculum circulare vel 
subcirculare, calcareum, spirale, anfractibus interdum 
lamellatis, nucleo excentrico. 
Shell globosely turbinated or conical, or cylindrically ob- 
long, variously umbilicated, sometimes smooth, some- 
times densely scabrously decussated, whorls generally 
rounded; aperture circular or pyziformly circular, lip 
reflected, rarely simple, sometimes frilled. Operculum 
circular or nearly circular, calcareous, spiral, whorls 
sometimes lamellated, nucleus excentric. 
The necessities of this work oblige me frequently to as- 
sociate several excellent genera under one head, and I 
shall have to group many of the genera of the great family 
of Cyclostomacea in this manner. Under the old generic 
appellation of Cyclostoma I include the species arranged by 
Pfeiffer under Cyclostomus, Otopoma, Choanopoma and 
Lithidion, all distinguished by having a spiral shelly oper- 
culum, of which the whorls are, in Choanopoma, curiously 
raised in lamelle. The geographical range of these groups, 
so far as regards the typical forms, are singularly local. 
Nearly all the globosely turbinated forms of Cyclostomus 
and Ofopoma are either from Madagascar or the neigh- 
bouring islands; two or three are from Natal and Zanzi- 
bar. But in the same group with these are some species 
of a quite distinct type inhabiting Europe and the Canary 
Islands, and several partaking of the very characteristic 
Choanopoma form which is peculiar to the West Indies, 
chiefly Jamaica and Cuba. The species of the little Zz¢hz- 
dion group inhabit Arabia and the island of Socotra. The 
Madagascar species have scarcely any sculpture, and little 
variation of colour. The predominant tone of painting is 
a yellowish drab, encircled about the periphery with a 
purple band. In Choanopoma the species are most elabo- 
borately sculptured with densely decussating scabrous la- 
mellee, and the lip is generally broadly flatly frilled. 
Species 1. (Fig. a, 6, Mus. Cuming.) 
CycLosToMa BICARINATUM. Cel. testd globoso-turbi- 
natd, fusco-cesid, spird subacute conicd, anfractibus 
undique obtuse liratis, medio remote bicarinatis ; aper- 
turd circulari, fauce intense atro-sanguined, labro late 
plano-dilatato, umbilicum interdum claudente. 
THE TWO-BANDED CycLostoma. Shell globosely turbi- 
nated, brown-grey, spire rather sharply conical, whorls 
everywhere obtusely ridged, encircled round the mid- 
dle with two distinct keels ; aperture circular, inte- 
rior black-blood-colour, lip broadly flatly dilated, 
sometimes closing the umbilicus. 
Soworsy, Thesaurus Conch. p. 120, pl. 26. f. 121. 
Tropidophora bicarinata, Pfeiffer. 
Hab. Madagascar. 
It will be seen by a comparison of the figures 1 @ and 
1 c of this well-known species, that the umbilicus is some- 
times closed and sometimes widely open; and that the 
lip, while generally partaking of the dark blood-colour 
of the interior, is occasionally white. 
Species 2. (Fig. a, 0, Mus. Cuming.) 
CYcLOSTOMA MULTIFASCIATUM. Cycl. testa globoso-tur- 
binald, casid, plus minus obscure purpureo-fasciatd, 
spird acute conicd, anfractibus subangusté rotundatis, 
levibus, ultimo circa umbilicum lirato ; apertura cur- 
culari, fauce atro-purpured, labro late dilatato, flaves- 
cente. 
THE MANY-BANDED Cyctostoma. Shell globosely tw- 
binated, grey, more or less obscurely purple-banded, 
spire sharply conical, whorls rather narrowly rounded, 
smooth, the last ridged around the umbilicus; aper- 
ture circular, interior black-purple, lip broadly dilated, 
yellowish. 
GrateLoup, Act. Soc. Linn. Bordeaux, vol. 11. p. 436, 
pl. 3. f. 3. 
Hab. Madagascar. 
In the earlier whorls of this species there is an exceed- 
ingly faint indication of two distinct thread-like keels, 
which quickly become altogether obsolete. 
Species 3. (Fig. a, 6, Mus. Cuming.) 
CycLostoma EBucHILUM. Cycl. testd globoso-turbinatd, 
soliduld, fusco-cesid, spird subabbreviato-conicd, an- 
fractibus angusté rotundatis, levibus, spiraliter lineari- 
impressis, ultimo circa umbilicum lirato ; apertura 
April, 1862. 
