80 THEBA CANTIANA. 
tuberculate, and there are three longitudinal dorsal rows of oblong shape; the 
LATERAL GROOVES are only faintly indicated, and no facial grooves are perceptible ; 
the MANTLE is deep grey, with paler veinings and specks, the margin of the pulmonary 
orifice dark grey ; the OMMATOPHORES are dully hyaline, closely covered with 
minute black specks, giving them a greyish-black tint ; they are widely divergent, 
and when fully extended are long, slender, and tapering, fairly bulbous at the apex, 
with black eye-specks ; the LOWER TENTACLES are somewhat bulbous at the end, 
about one-third the length of the upper pair, but more hyaline and transparent, 
apparently owing to the fewer and paler spots upon them ; the FOOT-SOLE is faintly 
trifasciate, due to the darker margins, when crawling the foot-fringe is distinetly 
separated by a groove and by its darker tint, due to the absence of the whitish spots 
present on the body generally ; when not fully extended the foot is very sprawling ; 
the locomotory slime is thin and colourless, though occasionally tinged with yellow. 
EPIPHRAGM is basally almost flush with the margin of the aperture, but on the 
upper margin is fixed inside the apertural rib ; the summer epiphragm is a trans- 
parent film, with a somewhat opaque and whitish appearance in parts owing to 
delicate cretaceous particles being dispersed within or over its surface in an arbor- 
escent manner ; the winter epiphragm is more calcareous, opaque, and solid. 
INTERNALLY, the cream coloured KIDNEY or renal 
organ is very long, broadly triangular above, narrow 
and tapering below; as seen through the shell in life 
it joins the light patch so conspicuous on the under- 
side of the body-whorl, but the russet-coloured arbor- 
escent veinings apparently spread over its outer sur- Hic. 114. —"Heart andeivenal 
face belong to the mantle membrane and not to the — organ of 7’/eba cantiana Mont. 
kidney itself. greatly enlarged. 
The REPRODUCTIVE ORGANS are chiefly remarkable for the apparent total loss 
of the dart-sae and its accessory gland and for the presence of an elongate C&CUM 
opening into the atrium, which is probably evaginated prior to pairing, and 
acts as an egersidium or excitatory organ, and thus usurping the chief function 
of the lost dart. 
The OVOTESTIS is composed of yellowish-white follicles in isolated groups and 
unilaterally arranged ; the HERMAPHRODITE DUCT is distally straight and slender, 
becoming thick, white, and sinuate as it approaches the vesicula-seminalis ; the 
ov. F : ue 
\ a dy  Ingl 
: (= | (Za lif? sb i 
fl : as Ce = 
= 
pe if 
fe / 
; i 
. o/ Ls 
Fic. 115. Fic. 116. 
Fic. 115.—Reproductive organs of 7heba cantiana Mont., xX 3. 
a.g. albumen gland ; d. degenerate dart-sac or sarcobelum ; ef. epiphallus. 
Fic. 116.—Proximal end of the reproductive organs of 7. cantiana, more highly magnified. 
Ai. flagellum; .g2. mucus glands; ov. oviduct; f.s. penis sheath; sé. degenerate dart-sac, sarcobelum 
or excitatory organ ; sf.d. sperm duct; sf. spermatheca; v.d. vas deferens. 
ALBUMEN GLAND is elongately linguiform, and terminally narrow, of a clear yellow 
or pale amber, occasionally tinged with greenish, of a gelatinous consistency, and 
indistinetly lobular; the OvipUCT is greenish-grey, closely sacculate, and some- 
times forming a sort of ruffle at the base of the albumen gland ; the PROSTATE or 
sperm-duct is of an opaque cream colour, or light ochreous, well defined, and some- 
what broad below; PENIS-SHEATH tumid, of a whitish colour, tinged in places 
