152 MILAX SOWERBII. 
of the rugze, thereby defining them very distinctly, and giving a reticulate appear- 
ance when the animal is contracted ; KEEL of an amber colour, very distinct and 
prominent on the back, the caudal end scarcely prominent, and hardly differing in 
colour from the general aspect of the body ; SHIELD about one-third the total length 
of the animal, granularly wrinkled; the protuberant, somewhat lenticular area 
extends to the posterior margin, is rounded on the left-side, but angulated on 
the right, and defined by a distinet sulcus, which is further accentuated by the 
closer aggregation therein of the black specks, which are sprinkled over the whole 
shield, but more especially upon the posterior mid-dorsal portion overlapping the 
keel; TENTACLES thick, short, conical, and black, their granulate surface finely 
sprinkled with ochre-yellow, apices swollen and somewhat oval with black eye 
specks ; NECK with the usual paired dorsal grooves, which on the forehead bifurecate 
and form four pale parallel lines; FOOT pale, and tripartite, the median area 
broadest and slightly darker posteriorly owing to its translucency ; FOOT-MARGIN 
smooth, yellowish-white, bounded by a distinet groove above, upon which rests a 
single row of tubercles, which are separated from the sides of the body by a deep 
channel. Mucus thick and viscous, and usually colourless, but when the animal is 
irritated or scalded may become of an orange tint; when the slime is removed the 
animal loses much of its yellow colour, which is thus partially due to its slime. 
SHELL oblong-eval, glistening white in colour, with a somewhat iridescent lustre 
in parts, usually slightly convex on the upper 
side, and in young shells correspondingly 
concave beneath, but often flat or slightly 
convex and somewhat irregular in more 
aged specimens; APEX or nucleus prominent, 
nearly median, and sub-terminal in_ the 
young but becoming more centrally placed 
as maturity advances ; the concentric LINES 
OF GROWTH variable, but sometimes very 
distinct and somewhat rugged and yellowish on the upper side. 
Length, 5 mill. ; breadth, 3 mill. 
INTERNALLY, the NERVE-RING has the inferior ganglia intimately fused to- 
gether; the supra-csophageal ganglia are 
Fic. 169.—Internal shell 
of Milax sowerbit, x 4. 
(Christchurch, Hants S., 
Mr. C. Ashford). 
large and elongately triangular with thickish } 
commissures ; the HEART, KIDNEY, anid 
LUNG cavity have the same general locative BiG) 170s eaNencs 
relations as in the field-slugs; the heart centres of M/. sowerbii 
is as usual on the left front of the kidney, (greatly enlarged). 
and the AORTA runs for a tolerable distance 
before dividing, as in Limax flavus; the 
kidney, however, is not a roundish sac, but 
is in two sections, one extending forward in the usnal way, the other being a long 
pointed lobe which extends over towards the right on the lung floor, beneath the 
ureter and the gut; the URETER is slender throughout its course. 
The REPRODUCTIVE ORGANS open exteriorly beneath the anterior margin of the 
mantle, about mid-way between the pulmonary aperture and the base of the right 
ommatophore ; the OVOTESTIS is generally concealed within the lobes of the diges- 
tive gland, the acini are whitish, large, globular, and rather loose, the ducts 
combining to form the main stem near the centre of the mass ; DUCT rather long, 
first portion slender and straight, becoming thick and convoluted as it approaches 
the small, curved, and clavate VESICULA SEMINALIS; ALBUMEN GLAND many-lobed 
and amber coloured ; OVISPERMATODUCT firmly united and strongly twisted ; 
ovipucT rather solid, buff or flesh colour, and very thick and difficult to unfold ; 
FREE OVIDUCT as long as the spermatheca and its duet, cylindrical and narrow, receiv- 
ing at its base the numerous delicate ducts from the multitude of anastomosing 
tubular glands, which constitute the vestibular prostate; SPERM DUCT broad, 
well-developed, milk-white or buff; VAS DEFERENS long, entering near apex of 
epiphallus ; the male organ is surmounted by a very stout, thick-walled, and 
muscular EPIPHALLUS, is annularly ridged internally, abruptly flexed and separated 
from the penis-sheath by a conspicuous sphincter muscle, denoted internally by a 
ring of white prominence and exteriorly by a raised ring; the PENIS SHEATH 1s 
narrow and eylindrical with thinnish walls and internal longitudinal ridges; it opens 
into the atrium or vestibule at the side below the opening of the stem of the sperma- 
theca, the SARCOBELUM or stimulatory organ being a small bent horn at the opening 
of the penis sheath into the atrium ; immediately above the sphincter a short stout 
RETRACTOR is aflixed to the convex side of the epiphallus; it arises from the dorsum 
