AGRIOLIMAX AGRESTIS. 
105 
Description.-—ANIMAL limaciform, with large but flattened tubercles; of a some- 
what uniform whitish or pale ochreous ground colour, but sometimes dull lavender 
or other tint, often mottled, speckled or reticulated with brown or black, and at 
times totally suffused with black ; BODY somewhat compressed and keeled towards 
the tail; TENTACLES dark coloured ; SHIELD more than one-third the total length 
of the animal, rounded in front and behind, concentric strive not deep, with the 
nucleus on the right side and towards the rear ; 
RESPIRATORY ORIFICE with a 
broad usually unpigmented raised ring, which is cut anteriorly by the anal cleft; 
SOLE pale and longitudinally tripartite, the side areas sometimes darker, especially 
towards the tail; SOLE-FRINGE separated as usual from the body by a furrow, 
containing a row of elongate tubercles, upon which the body tubercles rest uncon- 
formably. Mucus plentiful and viscous, often clear when crawling, but becoming 
milky-white on irritation, due to innumerable particles of carbonate of lime. 
Length usually about 35 mill. 
SHELL white, oblong-oval in shape, somewhat 
convex above and correspondingly concave below, 
usually rather thin ; NUCLEUS distinct and placed 
towards the left side of the posterior margin of 
the shell; concentric lines of growth perceptible, 
margin membranaceous. 
Length, 4 mill. ; width, 24 mill. 
ae 
« 
Fic. 117.—Internal 
shell of Agriolimax 
agrestis, X 4. 
(Markland Grip, 
Derbyshire, Mr. C. T. 
Musson). 
INTERNALLY, the cerebral ganglia are triangular in shape, spotted with brown, 
especially at the margins, the commissure grey or 
darkly spotted; the stomato-gastrie or buccal 
ganglia with longish commissure and dark-brown 
connectives ; the parieto-splanchnic ganglia are 
fused with the pedal ganglia, and both display 
short commissures ; the vestigial osphradium can 
be traced as a ridge and channel across to the left 
of the respiratory chamber ; the organ of Semper 
shows well-developed inferior lobes. 
The ALIMENTARY CANAL is triodromous, com- 
posed of the stomach tract and three intestinal 
coils; the INGESTIVE TRACT is the shortest, the 
(SOPHAGUS is also short, and the voluminous CROP 
of a light-brown colour, thin, and searcely fur- 
rowed, having the long and much-indented SALI- 
VARY GLANDS adherent to its sides. The last tract 
or rectum has, about mid-way, a short ececum on 
the right side generally directed backwards, and 
laid upon the upper surface of the crop. The DIGEs- 
TIVE GLAND is of an ochreous colour, the right 
lobe extending quite to the caudal end of the body, 
and in common with the whole intestinal mass 
has been subjected to a noticeable spiral twist in 
such a way as to indicate that an external shell if 
present would be a dextrally-coiled one. 
The CEPHALIC RETRACTOR origin- |||! { | 
ates in the median-line, behind the i \ 
‘lung, from three or more roots, which 
immediately unite to form a simple 
slender band, and divides usually but | 
not invariably about half-way. There \\ 
is considerable variation in the details \y ; 
of the fureation ; usually the BUCCAL 
and TENTACULAR branches separate 
at nearly the same point, but some- 
times the slender buccal branch is an 
offshoot of one or other of the ten- IN 
tacular retractors, or may arise from Fic. 120. 
the main-muscle before the tenta- 
| 
Fic. 118.— 
Nerve centres 
of <A. agrestis, 
showing otocysts 
x 8. 
(Christchurch, 
in Hants S., Mr. 
C. Ashford). 
we a 
op 
Fic. 119.— 
Alimentary canal of 
A. agrestis, X 2, 
with the salivary 
glands removed and 
showing the rectal 
coecum. 
(Christchurch, in 
Hants $3) Mr. iC 
Ashford). 
aa 
\ 
AN 
in\ 
Biesdale Fic. 122. 
Cephalic retractors of A. agrestis, X 2, exemplifying 
cular forking. The buceal retractor the variations to which they are liable. 
is always deeply divided in Enelish Fic. 120, represents an usual form. Fic. 121, a less 
forms, but not usually down to its — ¥su¥al arrangement. 
origin or root, as Dr. Simroth states is the case in the German specimens. 
23/1103 
Fic. 122, the unusual. 
