el a at oe ale |. eS. 
(‘“ 
lL 
The figure 115 in Sowerby’s ‘Thesaurus’ agrees more with this 
shell than with C. invelvulus, Mill., from which C. flavidus is distin- 
guished by the want of the spiral ribs, and by having the peristome 
not double, and coloured white. 
CycLoruorus punctatus, Grateloup ; Pfr. Mon. p. 67; Gray, 
Catal. Cycl. p. 45. 
Diam. maj. 24, min. 21, alt 19 mill. 
Leg. Bowring. 
MEGALOMASTOMA MYERSII, Haines, J. c. pl. 5. f. 9-11; Pfr. 
Suppl. p. 79 ; Novitat. Conch. pl. 18. f. 12. 
Long. 36-39 mill. 
Leg. House. 
OMPHALOTROPIS MACULATUS. 
Testa ovato-conica, acuta, striatula, parum nitens, olivacea, ma- 
culis fuscis triseriatis notata; anfr. 83, planiusculi, sutura 
minime profunda discreti, ultimus ovatus ; apertura oblongo- 
ovata, superne valde attenuata, acuta, peristomate simplice, 
margine externo parum arcuato, recto, acuto, columellari bre- 
viter expanso ; umbilicus pervius, angustus, carina alba, fusco- 
limbata cinctus. 
Long. 11, diam. 7, alt. apert. 6 mill. 
The outlines of this shell are somewhat similar to those of Assi- 
minea francisci, Wood, sp. I retain the name Omphalotropis, for 
which Pfeiffer has substituted “ Hydrocena” in the Supplement of 
his ‘ Monographia Pneumonopomorum,’ because I am by no means 
persuaded that the Eastern species with a keel round the umbilicus, 
and with a subvertical aperture, belong to the same genus as Hydro- 
cena cattaroénsis, Pfr., found in Dalmatia. 
Most of the species enumerated above have as yet been found only 
in Siam; but several are spread over a great extent of the large 
eastern peninsula, containing Birma, Assam, Siam, and Cochin China, 
as for instance, Nanina birmana, Helix tourannensis; a few others 
seem to extend beyond the peninsula to the neighbouring parts of 
India and China; but we may remark that these are species belong- 
ing to groups which are spread over most parts of the world, and 
which consist of species to be distinguished from each other only by 
the vague characters of size and proportions. 
The most striking natural groups represented in the fauna of Siam, 
as far as at present known, are exactly those which predominate 
in and are characteristic of the whole Indo-Chinese region and the 
adjacent islands, as Cyclophorus among the Cyclostomacea, Nanina 
and the great helicoid Bulimus (Amphidromus) among the Helicea. 
Bulimus siamensis is the only representative of a group which is con- 
fined to the continent, and is wanting, as far as I know, in the Eastern 
Archipelago. 
