#06 MOLLUSCA. 
TRITON MUNDUM. 
Testa parva, solida, oblongo-rhomboidea, straminea, epidermide tenui, 
sparsiin hirsuto induta: spira conica, anfractibus quatuor, convextus- 
culis, ultimo gibboso, tri-nodoso, in rostrum rectiusculum attenuato, 
costulis tribus et liris intermedianis cincto et filis continuis longitudina- 
libus decussato: apertura angusta, ovalis, dimidiam teste adequans ; 
labro crasso, tuberculis geminatis septem crenato ; columelld arcuata, 
posticé dentiferd ; fauce albo. 
Triton mundum, GouLtp; Proc. Bost. Soc. Nat. Hist., 11.145. May 
1849. Expedition Shells, 66. 
Ania pale cream colour, with a few marginal dots; head, tenta- 
cles, and siphon minutely ocellate; foot very small. 
SHELL small, solid, dingy white, of an oblong, subrhomboidal form, 
covered with a thin, fibrous, pale yellow epidermis, bearing scattered 
hairs. The back of the last whorl has three longitudinally compressed 
nodose folds, considerably elevated, so as to render the back gibbous ; 
varices (one on each whorl) well developed, broad, elevated, under- 
mined posteriorly: surface girdled by equidistant slender ribs, three 
on the upper and six on the anterior whorl, between each of which 
are three fine, raised lines, of which the middle one is the largest; 
there are also threads around the beak; every portion is sculptured 
with raised, approximate, longitudinal threads, which cross alike all 
the elevations and depressions, rendering the whole surface reticulate 
and granular. Whorls four, but when the apex is entire there are 
three smooth, hyaline, additional ones, moderately convex, with a 
well-impressed suture, the anterior one suddenly contracting to a short, 
direct, very slightly recurved beak. Aperture nearly half the length 
of the shell, narrow oval, acute at extremes; outer lip with seven 
bifid, tubercular scollops, which are prolonged towards the fauces ; 
pillar moderately arched, with a prominent ridge-tooth posteriorly, and 
with smaller ridges throughout. Whole aperture clear white. 
Length seven-eighths of an inch; breadth two-fifths of an inch. 
