8 ST. JAGO CAl'E DK VEKD ISLANDS. 



cliffs of less heiglit, but stretching out in advance 

 of those belonging to an older series : the height 

 of the cliffs thus affording a rude measure of the age 

 of the streams. 



During our stay, I observed the habits of some 

 marine animals. A large Aplysia is xevy common. 

 This sea-slug is about hve inches long ; and is of a 

 dirty yellowish colour, veined with purple. On 

 each side of the lower surface, or foot, there is a 

 broad membrane, which appears sometimes to act 

 as a ventilator, in causing a current of water to 

 flow over the dorsal branchiae or lungs. It feeds 

 on the delicate sea-weeds which grow among the 

 stones in muddy and shallow water ; and I found in 

 its stomach several small pebbles, as in the gizzard 

 of a bird. This slug, when disturbed, emits a very 

 fine purplish-red fluid, which stains the water for 

 the space of a foot around. .Besides this means of 

 defence, an acrid secretion, which is spread over its 

 body, causes a sharp, stinging sensation, similar to 

 that produced by the Physalia, or Portuguese man- 

 of-war. 



I was much interested, on several occasions, by 

 watching the habits of an Octopus, or cuttle-fish. 

 Although common in the pools of water left by the 

 retiring tide, these animals were not easily caught. 

 By means of their long ai"ms and suckers, they 

 could drag their bodies into very narrow crevices ; 

 and when thus fixed, it required great force to re- 

 move them. At other times they darted tail first, 

 with the rapidity of an arrow, from one side of the 

 pool to the other, at the same instant discolouring 

 the water with a dark chestnut-brown ink. These 

 animals also escape detection by a very extraordi- 

 nary, chameleon-hke power of changing their col- 

 our. They appear to vary their tints according to 

 the nature of the ground over which they pass : 



