HELIX POMATIA. AN LES} 
is no blind spot. Independently, however, of the iconoptic cephalic eyes, the skin 
itself is sensitive to light or photoskioptic, that is susceptible to sudden illumination 
and also acutely skioptic or responsive to sudden shading. 
The RHINOPHORES ! or organs of smell have their chief seat at the tip of the 
tentacles alongside the optical organs, though the anterior tentacles which are 
similarly innervated are also probably olfactory in function. 
The HEART is comparatively large, the muscular salmon-grey VENTRICLE being 
about double the size of the dull yellowish-grey AURICLE, to which it is joined by 
a narrow neck, 
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Fic. 279. Fic. 280. Fic. 281. 
Sense organs of Helix pomatia L. (greatly enlarged). 
FIG. 279.— Rhinophore or tentacular olfactory organ of Helix pomatia (after Flemming). 
é. eye; g.c. ganglion cells ; gs. ganglionic layer ; o/.ef. olfactory epithelium ; oZ.g. olfactory ganglion 
op.n. optic nerve ; fg.c. pigment cells ; 7. eye retractor; ¢.7. tentacular retractor. 
Fic. 280.—Auditory or equilibrating organ or otocyst of Helix pomatia (after Leydig). 
aud.n. auditory nerve; c. cut cle; ef. epithelium ; 7z. muscular layer; 7.c. epithelium cells with large 
fusiform nuclei ; of. otoconia. 
Fic. 281.—Cephalic eye of Helix pomatia (after Simroth). 
c. inner cornea ; cz. cutis ; ¢.é. crystalline lens; ef. epithelium, constituting outer cornea 3 0.772, outer 
inembrane or sclera ; of.”. optic nerve ; vez. retina; ¢.72. tentacular nerve. 
The PEDAL GLAND is compact and slightly thicker behind, with longitudinal 
ribs and numerous large folds which almost fill the lumen of the gland. A deep 
groove is seen posteriorly, and the floor of the excretory canal is lined with ciliated 
epithelium. 
The DART SAC or Stylophore? is a pearly-white, stout, and cylindrical sae, 
rounded at its distal end, with an especially thick and muscular outer coat, and 
is partially fused with the oviduct. 
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Fic. 282. Fic. 283. Fic. 284. 
Fic. 282.—Immature dart of //edix fomatia, showing the inequality of blades during deve'opment 6. 
Fic. 283.—Gypsobelum or love-dart of felix fomatia, X 6, with a more highly magnified oblique 
section showing the character and arrangement of the blades. 
Fic. 284.—The vaginal digitate glands and dart sac or stylophore of /Vedix pomatia. 
The GYPSOBELUM? or dart is tetraspathostylous, and is a strong regularly eurved 
glistening and sharply-pointed white weapon, nine or ten mill. in length, and fur- 
nished with four equisalient and regularly arranged blades (not arranged in pairs, 
as stated by some authors) with smooth, bluntly thickened edges, which terminate 
abruptly a little distance from the base, but gradually disappear towards the apex ; 
the pair of blades, however, which presumably represent an ancient dispathostylous 
condition, are sometimes fully formed before the more recently acquired pair have 
passed the rudimentary stage ; the base is moderately expanded and encireled with 
1 Monog. i., p. 151, f. 312. 2 Monog., i., p. 369. 3 Monog., i., p. 366. 
