NATURAL SCIENCES OF PHILADELPHIA. 37 



7iiciis and A. Cohimbianus ?, but a very stout, broad one to the 

 whole head, attached to the outer integument, below the buccal 

 mass, and running along some distance on the floor of the general 

 visceral cavit}'^, to which finally it becomes attached. 



In describing the genital organs I have used the terms applied 

 to the various organs by Dr. Leidy in the first volume of my 

 father's work on "The Terrestrial Mollusks of the United States." 

 Each form examined presented differences in these organs. They 

 all agree, however, in having a very large ovary. 



On opening the body of A. niger (plate XI. fig. c), 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, connected to the ovar}' by a long 

 epididymis (2). The testicle (1) 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 laud shells preserved in spirits. The above 

 described arrangement of the testicle is as usual in Limax, Avion, 

 and otiier slugs. It forms an excellent specific character for A 

 niger^ the position of the testicle being quite different in A. Cali- 

 fornicus and A. Golumbianus ?, as will be seen below. The epi- 

 didymis (2) is long, convoluted at the end nearer the ovary. The 

 accessory gland is shown in 3. The ovary (II) is large, yellow- 

 ish. The oviduct (8) and prostate (4) show no unusual characters. 

 The genital bladder (9) is large, oval, with a short duct (16). 

 The penis is in a short, stout sac (5), which has a bulb-like swell- 

 ing at its upper extremity, where the vas deferens (7) enters. 

 The latter organ has nothing of peculiar interest. A vaginal 

 prostate, or perhaps dart sac, is shown in 13. The external ori- 

 fice is described above (p. 34). 



The genital S3'stem of A. Californicus is figured in d of plate 

 XI. The testicle does not lie far away, imbedded in, or resting 

 on, the. upper lobes of the liver, but lies close against the ovary, 

 in the semicircle formed by the recurving of the apex of the 

 ovary upon itself. In this respect, the position of the testicle is 

 different from that of most slugs, and affords an excellent specific 

 character. The testicle (1) is kidney-shaped as it is covered by 

 its investing membrane. It appears to consist of closel}' bound 

 fasciculi of short, white, tubular, not aciniform caeca. The epi- 

 didymis (2) is short and still more shortened by its excessive 



