234 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Ariolimax niger, J. G. Cooper. 



Body long and narrow, blunt before, but little attenuated, and bluntly trun- 

 cated behind, with the termination of the body not arched down to the tail as 

 in Columbianus and Cali/ornicus, but rather erect, giving the 

 Fig. 133., appearance of being cleft, and showing much more plainly 



the caudal gland. Mantle quite small, bluntly rounded before 

 and behind. Color leaden below, blackish above. Length 

 contacted in spirits about 30 mill. Dr. Cooper gives 2h inches 

 as the length of the living animal. 



Ariolimax niger, J. G. Cooper, Proc. Phila. Acad. Nat. Sci., 

 1872, 147, PI. III. Fig. B, 1-4. 



Found in the California Region. I have received specimens from Oakland, 

 Bolinas, Santa Rosa, Healdsburg, Sonoma County. They all agree in their 

 genitalia, as well as in outward form. 



This species preserved in alcohol is most readily distinguished by its smaller 

 size, dark color, subcylindrical body, and especially by its bluntly truncated 

 posterior termination, which is decidedly cleft at the mucus pore. The nature 

 of the pore is described above (p. 229). 



Jaw (see p. 227). 



Ariolimax niger, also (PI. V. Fig. D), has the same type of dentition as A. 

 Columbianus ; the side cusps of the centrals are, however, more developed. On 

 one specimen I found marginal teeth with one inner stout, short, rounded cut- 

 ting point, and two shorter, rounded, side cutting points (see Fig. F), instead 

 of the usual long cutting point. This is the only variation in the dentition of 

 the genus which I have noticed. There are about 48 — 1 — 48 teeth. 



On opening the body of A. niger (PI. XII. Fig. F), the genitalia are found 

 in the usual place, the testicle lying quite at the rear of the visceral cavity near 

 the extreme point of the upper lobes of the liver, hardly imbedded in it, con- 

 nected with the ovary by a long epididymis. The testicle is globular in form, 

 composed of black, aciniform caeca. It contrasts in color with the dirty white 

 of the liver. Color, however, I have not found constant in the internal organs 

 of land shells preserved in spirits. The above-described arrangement of the 

 testicle is as usual in Limax, Avion, and other slugs. It forms an excellent 

 specific character for A. niger, the position of the testicle being quite different 

 in A. Cali/ornicus and A. Columbianus, as will be seen above. The epididymis 

 is long, convoluted at the end nearer the ovary. The accessory gland is small. 

 The ovary is large, yellowish. The oviduct and prostate show no unusual char- 

 acters. The genital bladder is large, oval, with a short duct. The penis is in 

 a short, stout sac, which has a bulb-like swelling at its upper extremity, where 

 the vas deferens enters. The latter organ has nothing of peculiar interest. A 

 vaginal prostate, or perhaps dart sac, is shown in p, g. The external orifice is 

 described above, 



