ARION SUBFUSCUS. 



19;") 



Fig. 210.— 

 Cephalic retractors 

 of A ri'on sub/uscus 

 X 2. 



(Christchurch, 

 Hams. S., Mr. C. 

 Ashford). 



The cephaTjIC eetkactoe,s of this 

 species are arranged as in Avion ater ; the 

 TENTACULAR retractors are broad, and 

 divide early for the ommatophore and 

 lower tentacle ; they are set obliquely, and 

 arise from seven to nine mill, apart, a little 

 in advance of the hind margin of the shield 

 on the posterior right and posterior left 

 side respectively ; the comparatively slender 

 PHAEYNGEATj retractor arises somewhat to 

 the right of the median-line, a trifle be- 

 hind the mantle margin ; it divides early 

 into two slender brancTaes, which become fixed to opposite sides of the buccal bulb. 



The REPRODUCTIVE ORGANS display a sepia-brown and lobular ovotestis, and 

 a creamy-white hermaphrodite duct, terminating in a distinct VESicula 

 SEMINALIS, which is grey, sometimes speckled with deep-brown ; the albumen 

 GLAND is semi-transparent and gelatinous, indistinctly lobular, and of pale 

 yellowish-grey colour ; the OVIDUCT is bluish-grey, broadly sacculate; bound to- 

 gether in convolutions, and showing a flesh-coloured ruffle at the base of tlie 

 albumen gland, which has the aspect of serai-gelatinous tubing, recalling the vesti- 

 bular glands of Milax soiverbii ; the sperm duct is creamy-white above, much 

 thickened and ochraceous below ; the long, slender, and semi-transparent VAS 

 DEFERENS passcs into the opaque-white and tapering bpiphallus, whose base is 

 encircled by a conspicuous raised ring, and within which is formed the very long 

 and serrate spbrmatophore ; the large and globose spermatheoa is at maturity 

 usually whitish, stiff', and hard, connected to the oviduct by tissue and small 



Fig. 211. 



^^^ 



at. 



Fig. 211. Fig. 212. 



Fig. 211.— Alimentary canal o! A. sub/uscus, with buccal hulb 

 and nerve-ring, X 2 (Christchurch, Hants. S., Mr. C. Ashford). 



Fig. 212.— Sexual organs of .-/. sub/uscus, X 2. 



Fig. 213.— Portion of the sexual system of ^. sub/uscus, show- 

 ing the vesicula seminalis, X 4. 



Fig. 2U.— Spermatophoreof .-!. sicbfuscus,X 6, with magnified portions showing details of structure 

 (after original drawing by Dr. Simroth). 



alb.gl. albumen gland ; at. atrium ; ep. epiphallus ; Ii.d. hermaphrodite duct ; ot. ovotestis ; m: 

 oviduct ; r. retractor ; sp. spermatheca ; s.d. and sji.d. sperm duct ; v.s. vesicula seminalis. 



muscular strands especially at apex of vesicle, the stalk is rather short and greatly 

 swollen basally, contracting where it joins the vesicle ; the free oviduct is at 

 first comparatively simple and slender, but enlarges abruptly and characteristically 

 in the latter part of its course, and shows internally a varied series of longitudinal 

 thickenings ; the genital retractor arises near the origin of the left tentacular 

 retractor, and becomes furcate, one branch being attached to the stem of the 

 .spermatheca, and the other to the upper part of the swollen free-oviduct. In this 

 species there does not seem to be any striking constriction of the atrium, which 

 is, however, invested by a well-defined yellowish glandular pad. 



The alimentary canal is triodromous, exhibiting the effects of the torsion of 

 the viscera, and greatly resembling the intestinal canal of the juvenile Arion ater; 

 the (ESOPHAGUS is usually about three mill, broad, and of a whitish colour ; the 



