<i4 IIAIUTS or THE CEPHALOPODA. 



The variations of form of the siphon are indisputable, and 

 one cannot doubt their influence upon the direction taken by the 

 animal, b\lt the marginal fins are not less useful; their undula- 

 tions commencing anteriorly when the animal moves forward, 

 and posteriorly in backward movement; they change suddenly 

 as the direction may be varied. The same tacts were remarked 

 with regard to the Calamary. 



Octopus mdgaris. During- 18(>7 I had the opportunity of 

 studying seven individuals, of which three were pretty large. 

 One of these quit his dwelling to explore the hole occupied I>v 

 another, who irritated, changed color and endeavored to seize 

 the intruder with one of the arms of his second pair. But 

 whether the cups failed to adhere to the body, or whether the 

 Poulpes possessed the means of disembarassing themselves, the 

 combat did not become serious. 



The second pair of arms (which are the most elongated) serve 

 principally for attack or defense; those of the first pair are 

 mostly cmpkryed in exploration ; they glide about among the 

 rocks, and if they come in contact with food, draw it towards the 

 mouth. 



The Poulpe moves but little during the day ; he execu 

 sometimes, a very singular mametivre; his arms make rapid 

 worm-like movements, writhing and twisting together. 



The variations of color occur occasionally without apparent 

 cause. I have seen, but only once, a Poulpe present a dee]) 

 vinous color upon one-half of its head and sack, whilst the 

 other half preserved a pale grayish tint. 'When Hie body be- 

 comes t uberculated. a sharp tubercle may be seen at the 

 ext remity of the sack. 



The I'onlpcs are very voracious. They were given daily a 

 quantity of Gardium edule. which they sei/ed and held close to 

 their mouth, concealed under the interbrachial membrane at the 

 base of the arms. After a variable period, but lit tie surpassing 

 an hour in duration, they rejected the valves, opened, and con- 

 taining only some remains of the mollusk. These valves were 

 perfectly in! act-; one could not perceive any fracture or trace of 

 teeth; the I'oulpes then possess some means of causing their 

 victim to relax its retractor muscles and open its shell perhaps 

 the victim is asphyxiated. A crab taken from a I'oulpe one or 



