HYGROMIA HISPIDA. 19 
the somewhat indistinct DORSAL GROOVES enclose a row of elongate tubercles, and 
there is no perceptible trace of facial or lateral furrows ; the slightly darker sub- 
dorsal lines are due to the tentacular retractors being visible through the skin, 
and are most perceptible by transmitted light. The MANTLE is grey, with darker 
grey and white mottlings, which are sometimes visible through the shell. The 
MUZZLE is somewhat elongated, the upper and lower TENTACLES being well 
separated ; OMMATOPHORES long, slender, and divergent ; lower tentacles short ; 
FOOT-SOLE long and narrow, of an almost uniform pale slate colour, but darker in 
front, marginally paler, but occasionally showing a darker submarginal line, and a 
distinctly crenulate margin. The EPIPHRAGM is thin and crinkled, beset with 
calcareous particles, and is affixed slightly within the aperture. 
INTERNAL ORGANIZATION—The HEART is small and white, the RENAL ORGAN 
buff or cream-coloured at the margins with dark brown spots or blotches, the 
central vein with lateral ramifications. The DIGES- 
TIVE GLAND is whitish, light buff or reddish-brown, 
the hepatic artery tinged blue, the intestinal folds 
olive-brown or greyish-white, perhaps in corre- 
spondence with the colour of their contents. 
The TENTACULAR RETRACTORS, according to a 
dissection by Miss Marie V. Lebour, show the un- 
usual feature of a trifid basal division of the tenta- 
cular muscles, the left OMMATOPHORE possessing a 
special muscular strip emanating from or near its 
origin or base ; the two main muscles divide some- 
what deeply ; that serving the left side bears only the 
retractor of the left lower tentacle and the broad 
sheaf of muscles for the anterior part of the foot ; f ; 
the tentacular muscle of the right side gives off Fic. 29.—Cephalic_and_ anterior 
lips to the right ommatophore and lower tentacle Ped! retractors of 1”. Aipida L.. 
S11} 8 = p (greatly enlarged), from a dissection 
and also a powerful trifid muscle to the foot. and drawing by Miss M. V. Lebour. 
The REPRODUCTIVE ORGANS show a fairly long and much convoluted HERM- 
APHRODITE DUCT; the ALBUMEN GLAND is of the usual shape, of a yellowish-white, 
pale lavender, or grey ; the OVIDUCT is pale 
and transparent and tinged with lavender; the 
PROSTATE or sperm-duct is opaque white or 
buff, well defined, and widest in the middle 
of its course; the FREE OVIDUCT is usually 
whitish-grey ; the SPERMATHECA and its duct 
are whitish tinged with buff, the spermatheca 
has a yellowish-white core, and the whole organ 
is sometimes minutely spotted with yellowish- 
white; the MUCUS GLANDS are somewhat 
rigid, and eight in number, disposed in four 
pairs around the vagina above the dart-sacs, 
they are about three mill. long, digitiform or 
tubular in shape, usually of a transparent 
azure white, with opaque creamy or buff cores, 
especially noticeable towards the slightly 
swollen extremities, and are joined to the 
vagina by a constricted neck; the PENIS- 
SHEATH is whitish-grey, tinged with azure, 
and minutely spotted, very swollen in shape Fic. 30.— Reproductive organs of 
and distinctly constricted at its junction with  //vsvomia Renae enlarged i 
the ATRIUM; the EPIPHALLUS is equal in Piet aes GES Bi eS ne 
length to the penis-sheath, of similar colouring, duct; o#. ovotestis; f.s. penis sheath; 7 
and boldly twisted towards its distal end,  penial retractor; sf. spermatheca; s.d. 
which would indicate that the spermatophore. SPerm duct or prostate. 
when discovered will show a corresponding peculiarity ; the FLAGELLUM is com- 
paratively short and stout and also partakes of the same pigmentation as the 
related organs. 
The STYLOPHORES or dart-sacs are bilobed and laterally paired clavate structures 
of a yellowish or whitish colour, finely spotted with brown, and placed on opposite 
sides of the vagina; they are each composed of a larger functional outer sac, each of 
which secretes and contains a dart, and also possesses a smaller or inner sac or 
lobe which is usually somewhat more opaque than the outer lobe and is always 
empty, showing no signs of having ever possessed a dart, so that it is not improb- 
