110 Mr. A. Adams on the Animals of certain Mollusca, 
Hydrobia and Amnicola, The rostrum is large, thick, and 
annulated, and, when the animal is crawling, is extended beyond 
the fore part of the foot. The tentacles are strong and subulate, 
and the eyes are large, prominent, and black, on the outer side 
of their bases. The foot is oblong and moderate, and strongly 
auriculate on each side in front; the sole and operculigerous 
lobe are simple. The operculum is subspiral; it is thick and 
shelly, and is composed of three rapidly enlarging whorls. 
I discovered the species S. punctosiriata, A. Adams, crawling 
slowly on the moist soil at the roots of grass, between high- and 
low-water marks, on the banks of the river Yang-tse. It appears 
to be very sluggish and inactive in its habits. 
In Borneo I found another species, S. olivacea, A. Adams, 
adhering to the under surface of dead leaves, and crawling about 
the soft mud by the sides of ponds. The nature of the opercu- 
lum places this genus in the same group as Hydrobia, and not 
in the family Viviparide, where my brother and myself have 
arranged it, judging from the similarity of the shell to that of 
Bithynia. 
Associated with these little Stenothyre, im considerable num- 
bers, was a species of Assiminia, of large size, and, I believe, at 
present unnamed, if it be not 4. Francisca of Gray, from India. 
The animal of this species progresses very much in the same 
manner as Truncatella, by means of its broad muzzle and short 
rounded foot. Short cylindric peduncles arise from swollen 
conical bases, wide apart on the upper surface of a flattened 
head, beyond which a dilated muzzle, bilobed at the end and 
ringed with black-brown lines, extends far beyond the front 
edge of the foot. A line is conspicuous on the sides of the 
peduncles, indicating the union of the tentacles and eye-pedicels. 
The eye, with a pale iris and a large black pupil, is placed at the 
end of an oblong bulb. The sides of the foot are marked with 
lateral, wavy, light brown dotted lines ; the sole is ovate, ob- 
tuse at both ends, and of a dull dirty white. The operculum is 
thin, horny, subspiral, and rather pointed behind. 
Genus Umsonivum, Link. 
At Hakodadi I had an opportunity of examining the animal 
of Umbonium giganteum of Lesson, which occurs along the sands 
of the bay, but is extremely difficult to obtain alive without 
dredging for it. I found Dr. Gray’s account of the creature to 
be very correct in the main; but | imagine the simplest view of 
the nature of the veil is to consider it a dilatation of the left 
tentacle. The lateral membrane in this species has four fila- 
ments on each side, whereas in U, vestiarium, Linn. (Rotella lineo- 
lata, Lam.), Dr, Gray mentions only three. The eye-peduncles 
