LIMAX ARBORUM. 9] 
and thick, with median inflation, cushioned with gelatinous matter, and possessing a 
white horn-shaped glandular appendage of variable length at its apex, but as the 
seminal element is transferred free, this flagellate slime-gland has nothing in common 
Fic. 110.—Penis-sheath 
of Limax arborunt \aid 
open, showing the internal 
structure (after Simroth). 
fi. flagellum; v.d. vas 
deferens ; Z. internal pro- 
Fic. 108. — Alimentary jection. 
canal of Limzax arborum 
(somewhat enlarged). 
Fic. 109.—Sexual organs of Limax arborum, xz. ulb.g. albumen gland; aé. atrium; _/7. flagellum ; 
h. heart; #. kidney ; of. ovotestis; ov. oviduct; . prostate; Z.s. penis sheath ; 77. retractor muscle ; 
sf. spermatheca. 
with the flagellum of the Helicide, in which group it is concerned in the formation 
of the spermatophore; internally, the penis-sheath shows two prominent longitudinal 
muscles, and frequently a linguiform projection, which may serve as a sarcobelum.! 
The penis retractor is a powerful muscle, attached to the lung floor in front of the 
cephalic retractor; SPERMATHECA pyriform, and opening into the atrium. 
The CEPHALIC RETRACTOR arises as usual from beneath the hind margin of the 
shield, and runs nearly half its length undivided ; it then usually separates into three 
branches ; the right and left TENTACULAR and the PHARYNGEAL muscles; the 
pharyngeal bifurcating soon after its separation. The retractor to the pharynx 
does not always separate fromthe main stem simultaneously with the tentacular 
branches, but may do so a little before or after the tentacular divarication. 
The MANDIBLE or jaw is about a millimetre ges 
wide, not so convex as those of the allied species, 
of a yellowish brown colour, smooth and delicate 2 
in texture, with rounded ends, and with a very . ae 
wide, slightly projecting and blunt median beak Bite SET andivle on law ob E77a7 4 
ae 2) arborumn, X 16. 
or rostrum, (Christchurch, Hants. S., C. Ashford). 
The LINGUAL MEMBRANE in ordinary specimens is about four mill. long and two 
mill. wide, the transverse rows being arranged in the form of a well-defined printer's 
‘‘brace”; the median row shows obscurely tridentate teeth, the mesocone exception- 
ally broad and strong, and the ectocones ill-defined and without perceptible cutting 
points; the lateral teeth are also remarkable for the well-marked mesocone and the 
indistinct side-cusps; the marginals are sinuate in shape, and at first distinctly uni- 
cuspid, but towards the outer rows an ectocone may be perceived on many of the 
teeth, the extreme marginals being, however, simply aculeate. 
» + 
‘o J Cy ae 
LY 8 re » ' m ‘ a ” 2 / {3 
\ — 
Fic. 112,—Representative denticles from a transverse row of the lingual teeth of L. arborum, X 120. 
The animal collected at Christchurch by Mr. C. Ashford, and the palate prepared by Mr. W. Mess. 
The obliteration of the side-entting points on the median and lateral teeth is an 
attribute of maturity, as the teeth of the young are, according to Miss Esmark, 
always provided with lateral points. 
The formula of a Christchurch specimen is Cat1 Osi +10+e* % 10515-4835, 
= 3 2 -2 
1 Monog. i., p. 365, f. 667. 
