Chap. IX. MOLLUSCS. 325 



" cons, ne saurait mettre en doute la seduction deployee 

 "dans les mouvements et les allures qui preparent et 

 " accomplissent le double embrassement de ces her-* 

 " maphrodites." These animals appear also susceptible 

 of some degree of permanent attachment : an accurate 

 observer, Mr. Lonsdale, informs me that he placed a 

 pair of land-shells (Helix pomatia), one of which was 

 weakly, into a small and ill-provided garden. After a 

 short time the strong and healthy individual disappeared, 

 and was traced by its track of slime over a wall into an 

 adjoining well-stocked garden. 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 disap- 

 peared 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 

 everv 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 Cuvieras a parasitic worm under the name 



2 See, for instance, the account which I have given in my ' Journal 

 of Kesenrches,' 1845. p. 7. 



