48 HYGROMIA FUSCA. 
Description—ANIMAL elongate and varying in colour between a vinous-yellow 
and blackish or greenish-grey, but darkest anteriorly, and there is no trace of facial 
rooves ; the BODY is more or less tubereulate ; the DORSAL FURROWS are fairly 
distinet: OMMATOPHORES long and slender; LOWER TENTACLES blunt and short; 
there are dark subdorsal lines, one on each side the body, which run to near the 
tips of the tentacles, and are due to the TENTACULAR RETRACTORS being perceptible 
through the semi-transparent tissues; the MANTLE is marbled or speckled with 
white and brown. 
When crawling, the PULMONARY RETICULUM is clearly visible through the 
pellucid shell and tissues, and extends backwards about half-a-whorl from the 
APERTURE up to the long and narrow yellowish RENAL ORGAN ; the HEART, which 
is closely adjacent, clearly displays its responsive pulsations. Beyond the renal 
organ, the MANTLE is black, finely speckled with yellowish or greyish, the spots 
increasing in number until the general effect towards the apex of the shell becomes 
reversed, and shows as yellowish-grey with black spots. The margin of the aper- 
ture usually shows a black patch extending along and near to the suture. 
SHELL subglobose, subconical above, convex beneath; WHORLS 44 to 5 gradually 
enlarging in size, the last whorl ample and subangulate at the periphery, suture 
distinct but not deep ; shell substance very thin, fragile, and of a deep transparent 
amber colour, but exceedingly glossy ; trausverse STRLZ irregularly plicate or 
corrugate with intermediate finer growth lines; spiral striz ill-defined and slight, 
but most perceptible in the umbilical region ; APERTURE obliquely and broadly 
lunate, outer lip sharp and thin, abruptly inflected above and much reflected 
basally, partially concealing the very minute umbilical perforation. Diam., 9 mill. ; 
alt., 55 mill. EPIPHRAGM extremely thin and vitreous. 
Dr. J. E. Gray describes the hairy investment as so fine and deciduous that the 
surface is frequently supposed to be without hair. Reeve describes the shell as 
“minutely hairy,” and the late Mr. G. Sherriff Tye has stated that the hairs are 
thickly clustered on the surface of the shell, are very short and bent towards the 
aperture, but are only perceptible under a high magnifying power. 
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VARESE OSA 
Fic. 68. Fic. 69. 
Fic. 68.—Hair-like sculpture of the shell surface of Hygromia fusca, after a micro-photograph . 
by Mr. W. Bagshaw. 
Fic. 69.—Hairs from surface of the shell of Hygromta fusca (highly magnified), after a drawing 
by the late Mr. G. Sherriff Tye. 
A careful examination of the shell surface with a l-inch objective shows that 
the appearance of crowded hairs referred to by Mr. Tye is possibly due to the minute 
sculpture which, however, lies parallel to and not at right-angles with the growth 
lines as described by him, and are probably the fine strive referred to by Dr. Gwyn 
Jeffreys as found on immature shells and which he compared to ‘‘hair-cloth.” 
INTERIORLY, the GSOPHAGUS and STOMACH are greyish-white ; the LIVER or 
digestive gland dark brown, sometimes flecked with whitish, the hepatic artery not 
conspicuous, and the intestinal fold whitish ; the KIDNEY or renal organ is almost 
sagittiform in shape, of a salmon colour, speckled with yellowish-white, and the 
HEART has the junction of the auricle and ventricle almost filiform. 
The REPRODUCTIVE ORGANS show a large and white OVOTESTIS, which has its 
upper side partly imbedded in the brown or russet liver ; the HERMAPHRODITE DUCT 
is dusky-white or cream colour spotted with brown; the ALBUMEN GLAND is of a 
very pale greenish-yellow ; the OvIDUCT ochreous-grey ; the PROSTATE or sperm- 
duct whitish-buff of a granular aspect, and externally wider than the oviduct in 
parts; SPERMATHECA narrow, digitate, or lanceolate, of a whitish colour dashed 
with bluish, and borne on a long and slender stem; PENIS-SHEATH short and 
