88 



HISTORY OF CRUSTACEA. 



CHAP. IX. 



of the third pair, two inflations furnished each with a 

 long seta, but that beneath this Nauplius-skin a very 

 different larva lies ready prepared, which in a few hours 

 bursts its clumsy envelope and then makes its appearance 



in a form " which 

 agrees in the seg- 

 mentation of the 

 body and in the de- 

 velopment of the ex- 

 tremities with the 

 first Cyclops-stage " 

 (Glaus). The en- 

 tire series of Nau- 

 plius-stages which 

 are passed through 

 by the free Copepo- 

 da, are in this case 

 completely over- 

 leapt. 



A final and very peculiar section of the Crustacea is 

 formed by the two orders of the Cirripedia and Khizo- 

 cephala. 6 



5 Fig. 55. Nauplius of Tetradita porosa after the first moult, magn. 

 90 diam. The brain is seen surrounding the eye, and from it the 

 olfactory filaments issue ; behind it are some delicate muscles passing 

 to the buccal hood. 



6 The most various opinions prevail as to the position of the Cirripedia. 

 Some ascribe to them a very subordinate position among the Copepoda; 

 as Milne-Edwards (1852). In direct opposition to tins notion of his 

 father's, Alph. Milne-Edwards places them (as Basinotes) opposite to 

 all the other Crustacea (Eleutheronotes}. Darwin regards them as 

 forming a peculiar sub-class equivalent to the Podophthalma, Edri- 

 ophthalma, &c. This appears to me to be most convenient. I would not 



Fig. 55. 



