8o CRUSTACEA CIRRIPEDIA 



Society's Transactions, Sir Eobert Moray describes what he takes 

 to be little birds enclosed in Barnacle shells, washed ashore on 

 the coast of Scotland : " The little Bill like that of a Goose, the 

 Eyes marked, the Head, Neck, Breast, Wings, Tail, and Feet 

 formed, the Feathers everywhere perfectly shaped and blackish 

 coloured, and the Feet like those of other Water -fowl, to my 

 best remembrance." Cuvier in his classification of the animal 

 kingdom included them in the MoUusca ; and it was not until 

 1830 that J. V. Thompson described their larval stages, and 

 showed conclusively that they belonged to the Crustacea. Since 

 the work of this naturalist a number of observers have securely 

 founded our knowledge of the group, but we may especially 

 mention the epoch-making works of Darwin,^ Hoek,^ and latterly 

 of Gruvel.^ 



The young Cirripede is hatched out from the maternal 

 mantle -cavity as a free - swimming Nauplius, a larval form 

 common to most of the Entomostraca and to some Malacostraca ; 

 the Cirripede Nauplius (Fig. 49) is characterised by the presence 

 of well - developed frontal horns, and usually by the long spiny 

 processes which spring from various parts of the body. As 

 an introduction to the study of the group, it will be well to 

 follow the transformations of this larva in Lepas up to the 

 period when it begins its sessile existence. The liberated 

 Nauplii swim freely near the surface of the sea, and remaining 

 in this condition for several days are dispersed widely from their 

 birthplace ; they are then transformed by the process of moulting 

 into the second larval stage, known as the Cypris (Fig. 50), 

 from its resemblance to a bivalve Ostracod. The Cypris larva 

 continues to swim about by means of the six pairs of biramous 

 thoracic legs until it finds a suitable place on which to fix ; 

 in the case of Leipas fixation usually takes place on loose floating 

 logs ; the Cypris fixes itself by means of the first antennae, at 

 the bases of which a large cement -gland secretes an adhesive 

 substance. The biramous swimming legs are cast off, and 

 six pairs of biramous cirri characteristic of the adult take their 



logical origin to the legend, the Barnacle goose (deriv. Hibcmicula, hernicula = \rish 

 goose) being confounded with pernacula, bernacula, a little shell. 



1 " A Monograph of the Cirripedia," vols. i. and ii., Ray Society, 1851, 1853. 

 ^ "Rep. on the Cirripedia, H.M.S. 'Challenger,' " vols. viii. and x., 1883. 



2 "Monographie des Cirrhipedes," Paris, 1905, in which will be found full 

 references to literature. 



