[93.1]

[Letter not transcribed]

[93.2]

[Letter not transcribed]

[93.2v]

8

Chap. 9 Mollusca

four hours it returned, and apparently communicated the result of the its successful exploration; for both then started along the same track of slime and disappeared over the wall.

Even in the highest class of the Mollusca, namely the Cephalopoda, or cuttle-fishes, in which the sexes are separate, secondary sexual characters of the kind which we are here considering, do not, as far as I can find out discover, occur. This is a surprising circumstance, as these animals possess highly developed eyes sense-organs and have considerable mental powers, as will be admitted by every one who has watched their artful endeavours to escape from an enemy.1*(1) Certain Cephalopoda, however, are characterised by one extraordinary sexual character, name= that in the male the liquor seminalis collects within one of the arms or testicles tentacles, which is then cast off, and clinging by its sucking discs; to the female lives for a time and independent life. So completely does the cast-off arm resemble an independent a separate animal, that it was described by Cuvier as a parasitic worm under the name of Hectocotyle. But this marvellous structure must may be classed as a primary, rather than, as a secondary sexual character.

[Descent 1: 325-6: "Mr. Lonsdale concluded that it had deserted its sickly mate; but after an absence of twenty-four hours it returned, and apparently communicated the result of its successful exploration, for both then started along the same track and disappeared over the wall.
Even in the highest class of the Mollusca, namely the Cephalopoda or cuttle-fishes, in which the sexes are separate, secondary sexual characters of the kind which we are here considering, do not, as far as I can discover, occur. This is a surprising circumstance, as these animals possess highly-developed sense-organs and have considerable mental powers, as will be admitted by every one who has watched their artful endeavours to escape from an enemy.2 Certain Cephalopoda, however, are characterised by one extraordinary sexual character, namely, that the male element collects within one of the arms or tentacles, which is then cast off, and, clinging by its sucking-discs to the female, lives for a time an independent life. So completely does the cast-off arm resemble a separate animal, that it was described by Cuvier as a parasitic worm under the name of Hectocotyle. But this marvellous structure may be classed as a primary rather than as a secondary sexual character.
2 See, for instance, the account which I have given in my 'Journal of Researches,' 1845, p. 7."]