The Cambridge natural history . left arm. In Octopus, the third arm on the right side is subject tomodification. This arm is always shorter than the correspondingarm on the other side, and carries fewer suckers, but is furnishedat the extreme tip with a peculiar kind of plate, which connectswith the membrane at the base of the arm by a channel of skin,which probably conveys the spermatophores up to the tip. 1 Hist. Anim. v. 6 and 12, iv. 1, ed. Bekker, 1837. - On pourra constater si ce ne seraient pas des parties detachees de quelque ccplia-lopode dans Ic but de servir h. le fecondation, Hist.
The Cambridge natural history . left arm. In Octopus, the third arm on the right side is subject tomodification. This arm is always shorter than the correspondingarm on the other side, and carries fewer suckers, but is furnishedat the extreme tip with a peculiar kind of plate, which connectswith the membrane at the base of the arm by a channel of skin,which probably conveys the spermatophores up to the tip. 1 Hist. Anim. v. 6 and 12, iv. 1, ed. Bekker, 1837. - On pourra constater si ce ne seraient pas des parties detachees de quelque ccplia-lopode dans Ic but de servir h. le fecondation, Hist. Nat. Helminthes, 1845, p. 482. I40 IIERMAniRODITE MOLLUSCA, GENERATIVE ORGANS chap. In Octopus vvlgaris, the species referred to by Aristotle, thehectocotylised arm is short, tliin in its outer half and pointed atthe extremity, while tlie fold of skin is very white, and givesthe arm an appearance of being divided 1)y a cleft at the the same time, an nnnsual development of one or two suckerson the arm is not uncommon.^. Fig. 52.—Octoims lentus Baird, N. Atlantic, showing the peculiar formation of arm, (After Verrill, x ^.) It is believed that in the Tetraljrancliiate Cephalopoda.{Nautilus) a union of the four inner ventral arms may correspondfunctionally to the hectocotylising of the arm in the Dibranchiates. Hermaphrodite MoUusca.—(«) Monogoywpora.—The repro-ductive system in tlie hermaphrodite Mollusca is far more compli-cated than in the dioecious, from the union of the male and femaleorgans in the same individual. As a type of the Monogonopora,in wliich a single orifice serves for both male and female organs,may be taken the connnon garden snail {Helix aspersa), theaccompanying figure of which is ch^awn from two specimensfound in the act of union (Fig. 53). Beginning from tlie inside and proceeding outwards we havefirstly the hei-mapliroditc gland or ovo-testis (), a yellowishwhite mass of irregular shape, embedded in the liver (l.)
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
