ARION HORTENSIS. 211 



_ As Dr. ScharfF has pointed out, it can be distinguished from similarly- 

 sized specimens of Avion ater by its dark colouring, the young of ater 

 being usually light coloured, and the wriukles longer and broader, while 

 A. intermedius is readily separable by the possession of the peculiar little 

 conioally-pointed body wrinkles, which have earned for it the title of the 

 "hedgehog snail." 



Internally, this species is distinctly separated from its closest ally, 

 A. circumscriptus, by the large globular spermatheca, and the extra 

 long and almost uniform free-oviduct, a feature which distinguishes it 

 also from the other species. 



Description. — Animal of somewhat cylindiiual shape, but dorsally depressed, 

 about thirty mill, long when fully extended, of an uniform bluiah-grey or slate-grey 

 colour, darkest and almost black mid-dorsally, shading paler towards the foot, with 

 a black lateral band, wliich is most indistinct at its lower margin, and extends the 

 whole length of the body and shield ; bodv TtJBERCLES comparatively broad, and 

 forming about twenty-four longitudinal rows at each side; SHIELD comparatively 

 small and coloured like the body, rounded in front and broadly rounded behind, 

 finely shagreened, with the lateral banding of the body continued as a somewhat 

 lyre-shaped black banding, which arches over the respiratory orifice; head dark, 

 especially in front; NECK pale; ommatophores dark, due in great part to the dusky 

 retractors ; sole not visibly tripartite, yellowish or orange ; eooi'-kringe similarly 

 coloured, with slight transverse furrows which are sometimes faintly pigmenteil. 



Dekmal-MUCUS yellowish or orange coloured and very viscid, the caudal and 

 locomotory mucus colourless, the latter stained by admixture with the yellow 

 tegumentary slime. 



The shell is described, especially by Italian authors, as well developed and 

 solid, but in our British specimens it is usually soft and gelatinous, and only dis- 

 tinguishable by its colour, but hardens by exposure ; occasionally, however, distinctly 

 solid transparent stones may be found. 



Internally, the body cavity is of a slaty-blue colour, except above the foot- 

 sole, which shows an ochreous tint, minutely spotted with white ; the SUPRA-rEDAL 

 GLAND extends half the length of the body during repose, but during active move- 

 ment it is only about one-third the total length of the whole body. 



The CErHALlC RETRACTORS are broader and flatter 

 than in Lim^ix, but of the usual Arion type. The 

 TUNTACUL.VR muscles spring from widely separated 

 points, anil the lower tentacular branch is strongly 

 develojied ; tlie right tentacular muscle arises from 

 the shield at the right margin of the kidney, while 

 the left muscle springs from a corresponding point 

 on the left margin, their roots bein" thus separated 

 by the whole width of the kidney ; ^le pharyngeal 

 retractor arises from the dorsal skhi on or to the right 

 of the median-line, quite behind the lung, about three F'g. 222.— Cephalic retractors 

 mill, posterior to the tentacular muscles, and is cleft of--'""" /'«•'""« ^i'-, x i. 

 about mid-way, for attachment to opposite sides of the buccal bulb. 



The ALIMENTARY SVSTEM is, as in all its congeners, triodromous, although not 

 exhibiting a very pronounced spiral torsion ; the INGESTIVE TRACT extends posteri- 

 orly beyond the succeeding coils, and terminates in the true stomach ; the 

 CESOPHAGUS is fused to the PHARYNX from its origin up to the CEREBRAL 

 GANGLIA ; the CROP is voluminous, and pale brown in colour, with the whitish 

 SALIVARY GLANDS attached to its sides ; while the left lobe of the DIGESTIVE 

 GLAND is, as is usual, directed backwards. 



The REPRODUCTIVE ORGANS show a roundish or oval OVOTESTIS, with few acini, 

 and is often of a dark colour, especially between the lobules, where it is frequently 

 of a deep purplish-black ; the DUCT is whitish or yellowish, long and slender, but 

 becoming thicker and somewhat convolute as it approaches the gelatinous and 

 greyish ALBUMEN GLAND ; the OVIDUCT is sacculate and white, closely attached to 

 the SPERM DUCT which on separation forms a short VAS DEFERENS ;_ the FREE 

 OVIDUCT is of great length and usually slender, except at the base, it is often, 

 before distention, doubled upon itself in an S-like form ; the bpiphallus is short 

 and conical, white basally, ringed above with dark grey, and merges almost 



