58 LAND AND FRESHWATER 
fig. 8(A), is some distance (3 mm.) behind it, and concealed by the 
mantle, its position being quite on the right posterior margin. 
Length of spirit-specimen 16-0, mantle 11-0, breadth 5°5 mm. 
i i 0°65 _,, 0-45, ,, 0:23 inch. 
The shell (fig. 4) is ovate, thin, flat, transparent, milky white, 
with close concentric ridges of growth, very thin and delicate on the 
margin; the apex rather more solid and quadrate at that end, the 
nucleus being on the right margin. 
Size: Major diam. 5:0 mm., minor diam. 3:3 mm. 
: 0-20 inch, 4 0°13 inch. 
Odontophore &c. The buccal mass (fig. 6) is large; the strong 
retractor muscle has its attachment, together with that of the eye- 
tentacles, in the usual position at the posterior side of the mantle- 
margin; but the posterior portion of the buccal mass is very 
different to what we find in other species: it is more truncate; and 
that part where the lingual ribbon takes its origin, and which in 
all species I have hitherto examined presents a shortish blunt knob- 
like process, in this species is represented by two coils, which are 
really the posterior edges of the lingual ribbon, turned up on each 
side and coiled on itself inwards. The lingual ribbon is broader 
than it is long; and 92 rows were counted, each containing at least 
530 teeth. 
265.1. 265. 
The central tooth (fig. 8) is 4-cuspid and much hooked. The 
laterals are all alike, very gradually becoming smaller on the outside ; 
they bend over in a claw-like form, and are edged with four cusps, 
of which the two outermost are slightly longer than the two inner ; 
avery minute cusp can just be discerned in some of the largest 
laterals near the centre, at the exterior base of, and next the first 
long inner cusp. 
The jaw (fig. 7) is very peculiar, Itis a very dark umber colour; 
the cutting or frontal edge forms an oblique angle; and the muscular 
attachment is very strong and extends back at right angles, equal 
in length to the width of the jaw, which is T-shaped as in Suc- 
cinea &e, 
The heart (vide fig. 5, V) is situated on the left anterior margin of 
the mantle. The position of the anus is very far back on the right 
posterior side, quite removed from the neighbourhood of the respi- 
ratory orifice, its usual position in most genera; and this is perhaps 
the most interesting point in the anatomy of this species. The 
intestine terminates in a large expanded sac just within the aperture. 
Generative organs (fig. 9). The ovotestis, hermaphrodite duct, and 
albumen-gland were not made out. The oviduct (ov.) is much conyo- 
luted for a short distance, and then extends in a long straight duct 
to the generative aperture; the prostate is of same length, the vas 
deferens running parallel to the straight portion of the oviduct down 
to a short bulbous expansion, to which it is probable the retractor 
muscle is given off; but this was not found in either specimen 
examined. The spermatheca (Sp) is of very great length; a long 
