98 METAMOEPHOSES OF MAN 



the Siphonostomidse.* In both cases the truth was 

 arrived at by examining the animals as they emerged 

 from the egg, by contrasting them with larvae known 

 to belong with certainty to other Crustacea, and by 

 watching closely their various transformations. When 

 the results of these researches were first published, 

 they were received with some scepticism, but having 

 been confirmed by numerous observers, they are now 

 unquestionable, and no one can deny these naturalists 

 the honour of having been the first to reveal that 

 curious mode of evolution, which we have termed 

 recurrent development. f 



Uniting the observations of Darwin and his rivals, 

 we shall endeavour to describe the metamorphoses of 

 one of these Balsenidse, whose pointed, jagged shells 

 cover the rocks most exposed to the waves with a sort 

 of crust. 



From the egg laid by the mother there springs an 

 almost microscopic larva, whose narrow body is divided 



* " Micrographische Beitrage zur Naturgeschichte der wirbellosen 

 Thiere," 1832. 



f Among those who have added to the history of the develop- 

 ment of Cirrhipedia, I may mention the names of Bate, Burmeister, 

 and Goodsir, and especially that of Mr. Darwin, who has written 

 a most valuable work upon the entire group, — " A Monograph of 

 the Sub-class Cirrhipedia," — Publications of the Ray Society, 1854. 

 Three French naturalists also devoted themselves to this subject — 

 M. Souleyet who died when engaged in his researches ; M. Bou- 

 chard-Chantereaux, known by his works on mollusks ; and M. Hesse, 

 Commissaire de la marine. Of works on the Siphonostomidse, I 

 may refer to the valuable memoir of M. Van Beneden, in which he 

 brings together the researches of his predecessors and the results 

 of his own numerous and persevering investigations (" Annales des 

 Sciences naturelles," 1831), and the several communications which 

 he has since made to the "Memoires" and "Bulletins" of the 

 Academy of Brussels. 



