ARION CIRCUMSCRIPTUS. 229 
The ALIMENTARY SYSTEM has the usual triodromons intestinal coiling, but the 
tracts are shorter, and therefore do not so palpably shew the great spiral torsion 
to which the viscera have been subjected ; the G:SOPHAGUS is about three mill. in 
length, and fused to the PHARYNX; the CROP is dirty-brown, about nine mill. 
long, and two mill. in diameter, closely wrinkled transversely, with the white 
salivary glands attached to each side; the DIGESTIVE GLAND is light brownish- 
ochre, and forms the hindmost point, but a lobe reaches far forward. 
ass 
Fig. 234. Fic. 235. Fic. 236. Fic. 237. 
Alimentary canal and Reproductive organs of Avion circumscriptus Johnst. and 
Arion ambiguus Pollonera. 
Fic. 234.—Alimentary canal of A. circumscriptus Johnst. x 3. (Christchurch, Mr. C. Ashford). 
Fic. 235.— Reproductive organs of A. circumscriptus Johnst. x 3. (Christchurch, Mr. C. Ashford). 
Fic. 236.—Proximal end of Reproductive organs of A. azzbiguus x 4. Bardonecchia, Piedmont 
(after Pollonera). 
Fic. 237.—Proximal end of Reproductive organs of A. ambiguus var. armoricana x 4, Brest, 
France (after Pollonera). 
a.g. albumen gland ; ef. epiphallus ; of. ovotestis ; ov. oviduct ; s.d. sperm duct ; sf. spermatheca 
with retractor ; v.d. vas deferens ; v.f. vestibular gland. 
The MANDIBLE or jaw is rather more than a mill. broad, and much resembles 
that of A. hortensis in general aspect, but in the 
particular example was thicker in substance, and of 
deep brown colour. It is of the usual crescentic 
shape, and strongly arcuate from front to back, with 
about ten vertical ribs or thickenings, which strongly ; : 
denticulate the upper margin, and are more evenly 4 Fic. 238.— Mandible or ewae! 
= > : c. Avion circumscriptus X 20. 
distributed over the whole anterior surface of the (Stroud, Mr. E. J. Elliott). 
jaw than in A. hortensis; the lower half of the jaw ; 
is much more deeply coloured than the top, which is of an amber colour, with the 
darker ribs very apparent thereon. 
The LINGUAL MEMBRANE is about three mill. long, and about one mill. in 
width, and composed of about 125 slightly-curved transverse rows of denticles, 
each row formed by a distinetly tricuspid median tooth, the strong and well- 
developed mesocone with lateral expansions ; the lateral teeth are about seventeen 
in number, obscurely tricuspid, showing a powerful mesocone with lateral expan- 
sions, an enlarged ectocone, and a more than correspondingly reduced endocone, 
without cutting-point ; the marginals are bicuspid, bearing a strong mesocone and 
a distinet and pointed ectocone, while the few extreme marginals are quite embry- 
onic in character. 
34. 
YR TY A) AAA (8h pe 
Fic. 239.—Representative denticles from a transverse row of the lingual teeth of 4. circumscriptus 
* 180, The animal collected at Stroud by Mr. E. J. Elliott, and the palate prepared by Mr. Neville. 
The dental formula of a Stroud specimen collected by Mr. E. J. Elliott is 
TH+ a5 t+Et+h54779 +7 x 125 =8,620. 
