396 THE AQUARIAN NATURALIST. 



they are subsequently found forming a pair of leaf- 

 like expansions, placed between either side of the 

 body of the Barnacle and the lining membrane of 

 the shells (PI. VII. fig. 6). These leaves seem to be 

 composed of a layer of eggs irregularly placed, and 

 imbedded in a kind of soft texture, out of which, 

 when mature, they readily fall on its substance being 

 torn asunder ; indeed it at length becomes so tender 

 as to disappear entirely ; so that, after the period of 

 gestation is passed, no vestige of these leafy con- 

 cept acles is to be found. 



Few things could be more startling to the inex- 

 perienced naturalist than the appearance of the young 

 Cirripedes derived from these eggs when they are first 

 hatched; neither could any one imagine a priori that 

 they were the progeny of parents so completely dis- 

 similar :- 



" The diabolic youngling 



Comes out no callow birth, 

 Puling, defenceless, blind, and weak, 



Like bird or beast of earth, 

 Or man, most helpless thing of all 

 That fly, or swim, or creep, or crawl, 



But in his perfect figure ; 

 His horns, his dreadful tail, his sting, 

 Scales, teeth and claws, and everything, 



Complete and in their vigour." 



In this their first or larva condition the young 

 animal is quite free and active, resembling a tailed 

 Monoculus (PL VII. fig. 6, a), able to swim about 

 vigorously ; and for this purpose having three pairs 

 of natatory limbs, the anterior of which are simple, 

 the others bifid ; it likewise has its back covered with 



