64 IIAIUTS dh- TIIK CKIMIAI-OPUDA. 



The variations oi" i\n\n of tlic siphon aiv indisputable, and 

 one cannot doubt their influence upon I he direction taken by the 

 animal, but the ma ri>in:il lins nre not less useful; their undula- 

 tions commencing- anleriorly wlien the animal moves forward, 

 and posteriorly in backwai'd ino\ cnient ; they change suddenly 

 as the direction may be varie(|. The same facts Avere remarked 

 with re<i;u'd to the Cahimary. 



Octopus vulgaris. — Durint: iSdT 1 had the oi)portunity of 

 studying seven indivi(bials. of which three were pretty large. 

 One of these quit his dwelling to explore the hole occupied by 

 another, who irritated, changed color and endeavored to seize 

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

 whether the cu[)s failed to adiicre to the body, or whether the 

 Poulpes possessed the means of diseml)arassiug 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 i)air are 

 mostly emi)loyed in exjjloration ; they glide about anumg the 

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

 mouth. 



The Pouli)e moves ])ut little during tiie day; he executes, 

 sometimes, a very singular manceuvre ; his arms make rapid 

 worm-like movements, writhing and twisting together. 



The variations of color occur occasionally without apparent 

 cause, r have seen, but only once, a I'oulpe present a deej) 

 vinous c(»loi' upon one-half of its head and sack, whilst the 

 other half preserved a i)ale grayish tint. When the body be- 

 comes tuberculated. a sharj) tubercle may be seen at the 

 extremity of the sack. 



The Poulpes are very voracious. "^riu'V were given daily a 

 (piantity of Gardium edulr. wiiich tliey seized and held close to 

 their mouth, concealed undei' the interhrachial membrane at the 

 V»ase of the arms. After a varialile period, but little sur{)assing 

 an hour in duration, they rejected the A'alves, oi)ened, and con- 

 taining only some remains of the mollnsk. These valves were 

 jicrfectly intact; one could not perceive any fracture or trace of 

 teeth; the Poul|)es then possess some means of causing their 

 victim to relax its retractor muscles and open its shell — i)erhaps 

 tiie victim is asjthyxiated. A crab taken from a Poulpe oiu' or 



