Fig. 8. Generative organs of D. Johnstoni, spread o u t:—a, retracted penis; b, vas deferens;
; c, testis; d, oviduct as it leaves the ovary; e, e, dilated portion of the same; f y oviduct
near to the point of its union with the testis; g, g, semi pellucid 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; l, accessory spermatheca; m, copu-
latory channel or vagina; n, retracted penis-like organ in connexion with the stiletto;
0, 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;
by external orifice of the female channel; c, vaginal orifice; d} penis-like organ in
connexion with the stiletto; e, stiletto within its pouch; f 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 ganglionsy f , f , gastjjo-oesophageal ganglions; g, first or anterior collar;
h, second collar, or commissure uniting the supra- and infra-oesophageal ganglions;
1, 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; 5 th 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} l, 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.