“ 
20 HYALINIA LUCIDA. 
Description.—The ANIMAL is long and slender, attaining a length of 20 to 25 
mill., and a breadth of 24 to 3 mill. when @t fullest extension, and is obtusely 
rounded in front, and bluntly pointed behind, the TALL projecting slightly beyond 
the shell when crawling ; the Bopy is of a dark blue-grey or slate colour dorsally, 
paler at the sides ; the DORSAL GROOVES |! enclose a row of granules or tubercles, 
and originate a series of more or less perpendicular transverse sulci, which are 
limited below by the LATERAL GROOVES,? beneath which and also close by the 
mantle the body is semitransparent, grey, ant granulated ; the flattened rgosities 
covering the body are smaller and more numerous near the head, while the inter- 
stices of the rugze are translucent grey by transmitted light ; the MANTLE is of a 
semitransparent gelatinous grey, its apparent dark colouring being due to the blue- 
blaek body of the animal beneath ; it is darker around the RESPIRATORY ORIFICE, 
which region shows as a dark collar through the shell when the animal is extended ; 
SOLE trifasciate, side areas bluish-grey or bluish-black, mid-area grey, not usually 
sharply defined in life, but more distinet after the animal has been scalded ; 
CAUDAL GLAND longitudinal ; OMMATOPHORES moderately long, stout and conical 
at the base, minutely granulate, of a greyish colour, but appearing almost black 
owing to the dark RETRACTOR within ; LOWER TENTACLES short and grey. 
The SHELL is very depressly convex above, less convex below; of a dark fawn 
colour above, whitish beneath; very glossy, scarcely semitransparent, and com- 
paratively thick and strong, periostracum somewhat thick ; SPIRE composed of 
six to seven convex and gradually enlarging whorls, the last perceptibly expanding 
towards the aperture, the surface ornamented with fine but somewhat irregular 
striation, which is most pronounced towards the sutures ; UMBILICUS moderately 
and perspectively open, exposing the whole of the spire ; APERTURE semilunar and 
very oblique relatively to the shell axis, and sometimes showing a calcareous 
thickening within, which is most pronounced basally ; PERISTOME simple and 
direct, slightly reflected aronnd the umbilicus ; EPIPHRAGM very thin, transparent 
and membranous. oe 
Diam., 15 mill. ; alt.6 mill. Average weight, 14 grains. 
INTERNALLY, the NERVE 
COLLAR is characterized by a 
marked asymmetry of the 
visceral commissures, due to 
the loss of the abdomino- 
pallial commissures, caused 
by the approximation and 
fusion of the ABDOMINAL 
GANGLIA with that of the 
right PALLIAL nerve-centre, fae Y 
thus throwing the compound Fic. 37. Fic. 38. ote 
z _ 
terminal ganglia towards the I'ic. 37.— Renal organ and Se sg 
right side of the body; the heart of 47. éucida (Drap.), x 3. / 
HEART is formed by a large k. kidney ; a. auricle ; v. ventricle. com 
dark grey ventricle and a Hes oh) — Galas eibace Fic. 39.— Nerve ring, of 
smaller naler erey auricle; — st ae ae ae _Slands, 77, /ucida (Drap.), showing 
sma » pe grey auricle; SLOANE their character, ar- the buccal ganglia, the oto- 
it is situate close by the rangement, and point of entry cysts, and the obliquity of 
triangular KIDNEY or renal HOT ESV S the visceral chain, x 14, 
organ, which is very conspicuously salmon-coloured with a dusky streak down the 
right side. ‘ 
The REPRODUCTIVE SYSTEM shows a somewhat elongate, acinose OVOTESTIS 
with a seareely convolute but medially stout HERMAPHRODITE DUCT ; ALBUMEN 
GLAND linguiform, gelatinous and semitransparent, of a clear yellowish or reddish- 
amber, or even a pale slate colour; VESICULA SEMINALIS distinct and recurved at 
the apex ; the OVIDUCT is much folded, narrow above, more ample below, and of a 
clear bluish-grey ; the attached SPERM-DUCT or prostate is opaque-white, granular 
and of varying size; the slender VAS DEFERENS after passing the muscular strands 
binding it to the base of the penis-sheath enlarges abruptly and forms an elongate 
opaque-white vessel, with longitudinal stripings, beyond which to the junction with 
the epiphallus the duct is comparatively stout; the EPIPHALLUS is long, slender 
and twisted, and beset internally with longitudinal rows of rounded depressions: 
it narrows somewhat where it joins the PENIS-SHEATH, which is an inversely elub- 
shaped organ, abruptly contracted at its junction with the vestibule, and of a pearly- 
white colour, with opaque longitudinal stripes ; RETRACTOR MUSCLE long, slender, 
D>? 
1 Monog. i., p. 205, f. 405. 2 Monog., p. 205, f. 406. 
