§ 225. 255 
THE CEPHALOPHORA. 
2. The genus Aplysia has an apparatus of particular secretion, consisting 
of a group of pyriform follicles situated under the branchia, inside of the 
skin. Its excretory orifice is behind the female genital opening, and its 
secretion is a whitish liquid with attributive corrosive qualities. 
3. Many of the Pectinibranchia, and Tubulibranchia, have upon the 
upper wall of the cavity of the mantle, a row of folds which secrete an 
extraordinary quantity of viscous mucus which is not excreted through any 
particular duct. 
4, With several terrestrial Gasteropoda, the median line of the foot is 
occupied by a straight canal lined with ciliated epithelium, which ends in 
a large orifice situated under the mouth. On each side of this canal, are 
rows of follicles that secrete a granular mucus which, passing into its cav- 
ity, is excreted externally, probably by means of cilia. 
CHAPTER IX. 
ORGANS OF GENERATION. 
§ 225. 
The Cephalophora propagate solely by means of male and female genital 
‘by a narrow canal, with the prolongations of the 
digestive cavity which enter into the dorsal ap- 
Y ges, and their ined liquid is subjected to 
a process of respiration. But Nordmann (loc. cit. 
p. 33, Tab. IT. R. R.) has been unable to find any 
such communication between these two organs, 
with Tergipes, and he has distinctly seen the 
granular mucus which is expelled from the follicles 
from contraction, escape through an orifice on the 
extremity of each dorsal appendage. With deolis, 
according to Hancock and Embleton (loc. cit. p. 
“80, Pl. IV. ¥.), the product of these follicles is quite 
interesting. It contains elliptical vesicles which im- 
mediately burst when put in water, exposing a 
transparent cylinder, out of which a filament, 
sometimes of a spiral form, is projected as swift as 
lightning. They compared these bodies to sperm- 
atic particles ; but to me, they appear exactly like 
the nettling organs of Actinia. Hancock and 
Embleton have also seen and figured with Aeolis, 
acanal of communication between these follicles 
and the prolongations of the digestive canal, but it 
may be questioned if this was not an artificial 
formation produced by compression of these organs 
during the examination.* 
4 See Cuvier, loc. cit. p. 4, fig. 2, S.; Delle 
Chiaje, Memor. II. p. 56, Tav. II. fig. 2, 0. fig. 
3; and Rang, Hist. Nat.des Aplysies, p. 25. 
5 These muciparous organs described by Cuvier, 
with Buccinum (Mém. loc. cit. p. 5, fig. 3, f.) as 
* [ § 224, note 3.] See for further description, 
together with figures of these peculiar bodies con 
‘taining a spiral thread, Alder and Hancock, loc. 
cit. Part III. Pl. VILL. fig. 14 (Aeolis) ; they correct 
their former view (mentioned above) and admit, 
what I think is not in the least doubtful, that they 
Feuillets muqueuz, are also found with Murea 
(Eysenhardt, in Meckel’s Deutsch. Arch. VII. - 
p. 215, Taf. III. m. m.), Terebra, Turbo, Voluta, 
Cypraea, Harpa, Dolium, Cassis, Tritonium, 
&c. (Quoy and Gaimard, Voy. de | Astrolabe, loc. 
cit., or Isis. 1836, p. 35, Taf. IT. fig. 6, q. Taf. III. 
fig. 10, X. 18, m.). Carus (Museum Senckenberg. 
II. 197, Taf. XII. fig. 8, h.) has seen similar mu- 
cous folds with Magilus. With Vermetus, on the 
contrary, I have found only a single, but a very 
considerable, longitudinal fold which runs along 
by the side of the rectum and covers the excre- 
tory duct of the genital organs. 
6 This muciparous apparatus of Bulimus, He- 
liz, Limaz, and Arion, was announced in 1829, 
by Kleeberg, at the Congress of Naturalists at 
Heidelberg (Isis, 1830, p. 574); but it had not es- 
caped the observation of Dedle Chiaje with many 
Helicina and Limacina (Descriz. II. p. 10, Tav., 
XXXVII. fig. 17, x.). It is therefore surprising 
that it remained thus long unknown to other natu- 
ralists. The assertion of Kleeberg, that with Li- 
maz, and Arion, the mucous canal communicates 
with the venous system, I have heen unable to con~ 
firm by observations upon Arion. Leydig de- 
clares that this mucous canal with the terrestrial 
Gasteropoda is the seat of the sense of smell; see 
Schleiden and Froriep’s Notiz. IV. p. 24, or Ann. 
of Nat. Hist. XX. p. 210. 
are analogous to the nettling organs of the Polyps. 
Agassiz has carefully observed them, and they 
have all the characteristics of a true lasso-cell; to 
this I may add my own observations upon other 
Mollusca. — Ep. 
