2 INTRODUCTION. 



shown by Burmeister, in the shells in these two classes ; 

 and Cirripedes certainly have no more claim to a mantle 

 than have the bivalve entomostraca. 2d. " In the sexes 

 joined in one individual " but this, as we shall see, is not 

 constant, nor of very much weight, even if constant. 3d. 

 " In the body not being ringed ;" but if the outer integu- 

 ment of the thorax of any Cirripede be well cleaned, it will 

 be seen, (as was long ago shown by Martin St. Ange), to 

 be most distinctly articulated. 4th. " In having salivary 

 glands ;" but these glands are, in truth, the ovaria. 5th. 

 " In the liver being formed on the molluscous type ;" I do 

 not think this is the case, but I do not quite understand 

 the point in question. 6th. " In not having a head or 

 organs of sense ;" this is singularly erroneous : Professor 

 Leidy has shown the existence of eyes in the mature 

 Cirripede ; the antennae, though preserved, certainly 

 become functionless soon after the last metamorphosis ; 

 but there exist other organs of sense, which I believe 

 serve for smelling and hearing : and lastly, so far from 

 there being no head, the whole of the Cirripede externally 

 visible, consists exclusively of the three anterior segments 

 of the head. 



The sub-class, Cirripedia, can be divided into three 

 Orders ; the first of which, mainly characterised by having 

 six pair of thoracic cirri, includes all common Cirripedes : 

 these latter may be divided into three families, — the 

 Lepadidse, or pedunculated Cirripedes, the subject of the 

 present memoir; the Verruciclse containing the single 

 genus Verruca or Clisia ; and, lastly, the Balanidae, which 

 consist of two very distinct sub-families, the Balaninse and 

 Chthamalinse. Of the other two Orders above alluded 

 to, one will, I believe, contain the remarkable burrowing 

 genus Alcippe, lately described by Mr. Hancock, and a 

 second burrowing genus, or rather family, obtained by 

 me on the coast of South America. The third Order 

 is highly singular, and differs as much from all other 

 Cirripedes as does a Lernsea from other crustaceans ; it 

 has a suctorial mouth, but is destitute of an anus ; it has 



