HELIX NEMORALIS. AAT ET 
spermatic fluid, quickly turning yellowish on exposure. The filament is covered 
with fine longitudinal strive and furnished with four sharp but thin and transparent 
longitudinal ‘Tidges, which are least developed on the enlarged tract; the slender 
posterior filament is twisted similarly to the free end of the fli agellum. 
The ALIMENTARY SYSTEM is of the or- 
dinary triodromous type, with three intestinal 
tracts; the paired SALIVARY GLANDS are 
ample, of a white colour, and lobular, and 
about twelve millimetres long, adherent to 
and surrounding the crop, with elongate and 
slender ducts which are about the same length 
as the glands and debouch into the rear upper 
part of the mouth cavity; the GsSOPHAGUS 
and CROP are striped longitudinally with 
darker lines; the STOMACH is placed at the 
end of the ingestive tract and is a gradually 
enlarging receptacle, but terminates more 
abruptly behind, where the biliary ducts enter ; 
the RECTUM is long, slender, and direct, terminating as usual close by the 
respiratory orifice. 
Fic. 335.— 
Alimentary organs of 
Hlelix nemoratis L., 
KS: 
66. buccal bulb: s.g. 
salivary glands; st. 
stomach; 7. rectum. 
The PEDAL GLAND very compact and well developed. Longitudinal groove deep. 
The roof of canal with two rather long folds ; the epithelium of channel very short. 
The MANDIBLE or jaw is about two mill. or more from side to side, reddish-fawn 
in colour, shading to deep brown in the thicker and more solid parts, convex from 
the front backwards, very broadly crescentic, with some- 
what truncated and slightly attenuated and rounded ends, 
bearing from two to nine widely-separated but more or 
less prominent vertical ribs, but usually there are about 
five only ; the central rib is, however, usually insignificant, F1G. 336. —Jaw or Mandible 
the admedian ribs being much more distinct and prom- — of Hedix nemoralis L., x 8. 
inent, and strongly denticulating both margins, while (Christchurch, Hants-); 
frequently the others only crenulate the cutting edge, becoming obsolete and dis- 
appearing before reaching the upper margin, but all are grouped near the median 
part and increase in number with age. The strive or lines of growth are very delicate. 
Mr. H. Crowther has remarked that the character of the jaw is influenced by 
the environment ; as when the animal lives in exposed positions by dusty roadsides 
on carboniferous formations the jaw is always stronger, darker, and bears more 
numerous and thicker ribs, whereas when living in moist localities and feeding 
upon succulent herbage, the jaw is thin and the ribs fewer and more delicate. 
The RADULA is of the usual oblong shape, about five mill. in length and nearly 
two mill. in breadth, composed of about 140 flexuous transverse rows, each row 
containing about 89 teeth, and constituted by a median series of strong unicuspid 
teeth, flanked by about fourteen laterals, each bearing a powerful central cusp or 
mesocone, while a distinct though comparatively small ectocone becomes imag 
Fic. 337, eeenane denticles from half a transverse row ot teeth of Helix nemoralis 1. 
(highly magnified). The numerals above the teeth indicate their position in the transverse row. 
developed as the teeth recede from the centre of the radula; the marginals, which 
are preceded by a number of transitional teeth, gradually broaden “and become 
strongly and distinetly quadricuspidate, by the splitting of the mesocone and the 
increased development and bifurcation ot the eetocone, the outermost denticles 
regularly dwindling in size anjl the extreme marginal being minute and simple. 
The formula of a P ininetead dae prepared by Mr. J. E. Cooper was 
$9 414 41414 430 x 140 = 12,460 teeth. 
