n2 



ARION nORTENPIS. 



imperceptibly into tlie vas deferens, it secretes the sliort thick srERMATOPHORE, 

 whioli has a smooth, thin envelope, -without the serrated crest so conspicuous in 

 Arlon ater and A. siibfuscus ; the SPERMATHECA is globular, variable in colour, and 

 attached by its crown to the base of the ovisper:matoduct, the stem is short 

 and thick ; ATRIUJI with a well-defined ochreous vestibular gland ; the GENITAL 

 RETRACTOR arises from the dorsum, behind the kidney, but soon bifurcates, the 

 extremities becoming fixed to the stem of the spermatheca and the upper third of 

 the free ovidnet. 



X 2. 



Fig. 225, 

 (Christchurch, S. Hants). 



-Spermatophore o{ Arion IwrteTists F6r., Leipzic, greatly enlarged (from an original 

 Dr. SImroth). 



Fig. 223. Fig. 22i, 



Fig. 223. — Reproductive organs oi Arion hortensis Yt\ 



Fig. 224 

 drawing hi 



Fig. 22.5. — .Alimentary canal o^ Arion hoyieitsis F^r. , X 2. 



ot. ovotestis ; h.d. hermaphrodite duct; />r. prostate; v.d, vas deferens; ep. epiphallus ; a.g. 

 albumen gland ; ov. sacculated or glandular oviduct ; s/>. spermatheca ; vag. vagina ; at. atriuin ; 

 v.g. vestilmlar gland ; r.7/z. retractor muscles attached to spermatheca and free oviduct. 



Tlie MANDUiLE or jaw is about a mill, broad, and about half-a-null. wide, with 

 nan-ower but somewhat bluntly rounded ends, strongly 

 arcuate from front to back, of an amber colour, with 

 about ten \ertica] rib.s or thickenings, apparently 

 formed by overbippings of the substance of the jaw, 

 which crenulate the upper margin and sometimes the 

 lower margin al.so ; the darker ribs and the clearer 

 interstitial siiiu'os show distinct vertical stri.i" ; at 

 about one-third of tlie wiiltli of the jaw, a dark line 

 runs parallel with tlie cutting margin, slinwing the jioint of origin of the elasnia, 

 wliicli extends on to the roof of the buccal cavitv. 



The LiNcu.^L JtiQiBRAXE is about three mill, long and one mil), wide, consti- 

 tuted by about IIB somewhat curved transver.se rows of teeth, which diminisli 

 regularly m size to the margin of the membrane. The transverse rows are each 

 composed of a stiungly tricuspid median tootli, the strong yet somewhat slender 

 iJiesouune, with ilistiiict accessory lateral cutting expansions '; the lateral teeth are 

 about ten in number, oliscurely tricuspid, Out the endoconic cutting point is lost, 

 the nie.socone shewing the side expansions ; tlie marginals are nniciispid, siiowiiK' 

 the powerful mesoeone only, but towards the margin an ectoconic cuttino poiiU 

 again becomes distinctly perceptible, while the few extreme marginals .stilf retain 

 their embryonic cliaracter. 



Fig. 226.- Mandible or jaw of 

 Arion hortensis, x 20. (Christ- 

 church, Hants S., Mr. C.Ashford). 



V 



V 



i=» [7. I! 



a 





^"^ 



Fig. 227.-Representalive denticles from a transverse row of the lingual teeth of A. s,ih/uscus, X 180. 

 Ihe animal collected by Mr. C. Ashford, and the palate prepared by Mr. J. W. Neville. 



The formula of a Christchurch spechnen collected by Mr C Ashford is 

 7 + i^\ + i-<^ + ^ + |o, + 1.1 + 7 X 1 16 = 8,468. 



