IV 



ANATOMY 



which live in great numbers attached to rocks and other objects 

 between tide-marks, the body is constructed on a similar plan. sa\e 

 that there is no stalk, and the body is completely enclosed in a hard 

 calcareous box formed from the mantle, which, when the valves 

 are closed, as they always are during low tide, completely protect 

 the animal inside from desiccation or danger of any kind. Besides 

 the cement-glands situated in the peduncle, we can' distinguish 

 the generative organs, consisting of a pair of ovaries and testes, the 

 majority of Cirripedes being hermaphrodite. The testes open at the 

 end of an elongated median penis behind the thoracic limbs, 



-P 



tm 



e-- 



m 



-at 



a 



-gi 



B 



FTC. fji>. A, Dwarf male of XW/W///,,/ ,// A/are, 27 ; B, diagram <>t' Stalked 



l!;irn:i'-lc. a, IVdunele. ; nl, alimentary canal ; /<, hrain ; c, carina ; <'. remains of 

 Nauplius eye; .<//, cement -;_dand ; /;(, mantle cavity ; , its opening : /, ovary: 

 //, penis : .s-, scutiuii : /. testis ; //. tei-unm, seen iii A us tin- shaded Ixidy above 

 tin- reference-line of e and to tlie n^ht, of (lie earina, on the left of the liuuiv. 



while the ovaries, situated in Hie peduncle, have, paired openings 

 into the man! le-cavil y on either side, of the head. A pair of 

 maxilliiry glands or kidneys are present, and the alinienl.-iry 

 ejni;d is provided witli various digestive glands. Speei.-i] 

 branchial organs are not present in the Pedunculate Cirripedes, 

 hut ill the Operculate genera two branehiae. are I'orjned from 

 the plications of the internal surface of the mantle. There 

 is no contractile heart, and the circulatory system is poorly 

 developed. The Cirripedes are, badly furnished \\ilh sensory 

 organs; the remains of a simple Xauplius eye ma\ persist, 

 situated on the upper part of t he stomach, but 1 he chief sense- 

 organs are, the sensory hairs upon the limbs. 



The recent Cirripedes fall into six clearly delined Sub-orders. 



