FIXED MESSMATES. 55 



more than one contrast; all live as wanderers when they 

 first leave the egg, and they are hatched in such abun- 

 dance on the coast, that the water becomes literally 

 troubled with them. At the first period of their life, 

 they have a supple and elegant body, and fins admirably 

 divided, and the gracefulness of the postures which they 

 assume does not yield in beauty to those of the most 

 brilliant insect. After having spent some time in seek- 

 ing adventures, they are seized with disgust for a nomad 

 life; they choose a resting-place, and establish them- 

 selves by means of a cable which they afterwards 

 abandon, and shelter themselves in an enclosed retreat 

 for the rest of their days. Many cirrhipedes choose the 

 back of a whale or the fin of a shark, and make the 

 passage across the Atlantic or the Pacific in less time 

 than the swiftest steamboats. 



In many of these, recurrent development (I was about 

 to say degradation) sometimes proceeds so far, that their 

 animal nature becomes doubtful, and more than one of 

 them, having no longer any mouth by which to feed, are 

 reduced to a mere case which shelters their progeny. The 

 messmate very nearly takes its rank among parasites. 

 There are also cirrhipedes which live on different genera 

 of their own family ; and some species which are always 

 found in society with other species. Some also live as 

 messmates with each other; some of the Sabelliphili 

 have one of the sexes parasitical on the other sex. 



Crustaceans are usually dioecious; but because of 

 their manner of life, the cirrhipedes sometimes- unite the 

 two sexes and thus render the preservation of the species 

 more certain. The whole family of the Abdominalia, a 

 name proposed by Darwin, if I am not mistaken, have 



