DORIS. 



Fig. 8. Generative organs of D. Johnstoni, spread out : — a, retracted penis ; b, vas deferens ; 

 c, testis ; d, oviduct as it leaves the ovary ; e, e, dilated portion of the same ; /, oviduct 

 near to the point of its union with the testis ; g, g, semipellucid portion of the mucus- 

 gland ; h, opaque portion of the same ; i } female channel leading to external orifice ; 

 j, spermatheca ; k, its duct leading to the oviduct ; I, accessory spermatheca ; m, copu- 

 latory channel or vagina ; n, retracted penis-like organ in connexion with the stiletto ; 

 o, pouch of the stiletto ; p, duct leading from the same to a glandular sac, q. 

 9. External view of the partially exserted generative organs of D. Johnstoni: — a, penis; 



b, external orifice of the female channel; c, vaginal orifice; d, penis-like organ in 

 connexion with the stiletto ; e, stiletto within its pouch ; /, point of the same, partially 

 protruded; g, duct leading from the pouch to the glandular sac; h, h, lip of the 

 common orifice. 



10. The pouch and stiletto, as seen in the compressor: — a, outer pouch; b, inner ditto; 



c, c, stiletto ; d, d, its sheath ; e, duct leading to the glandular organ ; f, portion of 

 the retracted penis-like organ. 



11. The apex of the partially exserted penis-like organ much enlarged: — a, stiletto; b, b, its 



sheath ; c, orifice at the point of the same ; d, apex of the penis-like organ. 



12. Spermatozoa from the oviduct of D. tuberculata. 



13. Cerebral or cephalic ganglions and nerves of D. tuberculata : — a, a, cerebroid or sensorial 



ganglions; b, b, branchial ganglions; c, c, pedial ganglions; d, d, olfactory ganglions 

 e, e, buccal ganglions; /, /, gastroesophageal ganglions; g, first or anterior collar 

 h, second collar, or commissure uniting the supra- and infra- oesophageal ganglions 

 i, third, or great oesophageal collar; 1st pair of nerves go to the dorsal tentacles 

 2d pair supply the channel of the mouth and lips ; 3d pair go to the oral tentacles 

 4th and 5th pairs pass to the channel of the mouth and lips ; 5th pair likewise give off 

 branches which go to form the anterior collar ; 6th pair are the optic nerves ; 7th pair 

 the auditory; 8th, 9th, and 10th pairs supply the mantle; the 10th pair send a branch 

 of communication to the branchial ganglia of the sympathetic system; 11th, 12th, and 

 13th pairs supply the foot; 14th and 15th pairs go to the sides of the body below the 

 mantle; 16th and 17th pairs are lost in the buccal mass; 18th pair supply the tongue; 

 19th pair are given to the salivary glands ; 20th pair supply the top of the gullet ; 21st 

 pair pass down the gullet, and are joined to the ganglia of the sympathetic system of 

 the stomach; j, k } I, m, single nerves from the visceral ganglion ; the first and last of 

 these go to the sympathetic ganglions of the heart and branchiae, the second to those of 

 the generative organs, the third to those of the stomach. 



14. Eye of D. repanda : — a, optic nerve; b, pigment cup; c, general envelope; d, lens; 



e, cornea. 



15. Auditory capsule of D. aspera : — a, outer capsule; b, inner capsule, containing numerous 



otolithes. 



