EOL2-] H. J. FLuEuRE: Anatomy of Melo indicus. 407 
Pace has worked at Voluta musica, about the relationships of 
which there is some doubt. It is a West Indian form, whereas 
80%, of the species of Volutes live within a triangle having its 
extreme points at Ceylon, Japan and New Zealand. It has a 
fusoid, narrowly elongated operculum mounted on a distinct pad. 
This is also found in Neftuneopsis, Volutolyria and Lyria, but no 
trace of it appears to subsist in Melo. 
TI.— EXTERNAL CHARACTERS AND BRANCHIAL CAVITY. 
(Pls. xxviii--xxx, figs. I—5). 
The lack of adequate illustrations of the Rhachiglossa has led 
me to sketch this type from several points of view, both the 
specimens used being females. 
The foot is large and massive with a long definite anterior 
edge, grooved (pl. xxviii, fig. 2, Gr.) and glandular as usual. This 
type of foot can be compared with that of Natica, bulla, Scaph- 
ander, etc., being apparently in every case an adaptation to the 
burrowing habit. In this connection, too, the compact rolling of 
the spire above the foot is noteworthy. The disposition of the 
spire and the columellar muscle makes possible the wide opening 
of the branchial cavity on the animal’s right side (pls. xxviii and 
xxix, figs. r and 4) with the result that. the rectum opens well back 
on that side (pl. xxix, fig. 4, A.), and the other openings are also a 
good way off from the ctenidium and osphradium. ‘The roof of 
the cavity between the ctenidium and rectum has the usual mucus 
gland with oblique ridges in its surface. In one specimen, as also 
in a part of another sent, but not in the other complete one, there 
was a well-marked swelling (pl. xxviii, fig. 1) not far in from the 
edge of the cavity’s roof. 
The siphon (S.) is short and strong and possesses two tentacles 
at its base, one above and to the right (R.S.T.) and the other 
below and to the left (L.S.T.) of the gutter. 
The osphradium (Osph.) is situated in the branchial roof and 
is bipectinate, with its leaflets approximately parallel to those of 
the ctenidium and somewhat oblique to the incoming stream of 
water along the siphon. The leaflets are rather thinner and finer 
than those of the ctenidium. 
The monopectinate ctenidium (ct.) and the osphradium both 
curve round to the left as they go back. The leaflets of the 
ctenidium are long-based low triangles. 
The proboscis (Pr.) is fairly short and pleurembolic. Pl. xxviii, 
fig. I shows it expanded to some extent while pl. xxx, fig. 5 gives 
it in the completely retracted condition. ‘The great mass formed 
by the retracted proboscis and the sheathing body wall displaces 
the oesophagus (pl. xxx, fig. 5). When the proboscis is extended 
its wall continues back practically without a kink into that of 
the proboscis sheath. 
The lamina or fore-roof (Fore-R.) above the proboscis, men- 
tioned as a characteristic of the Volutes, is very well developed 
