480 TRANSFORMATIONS OF INSECTS. 



Now the pupae of the Cirripedes resemble greatly those of some 

 Crustacea which are called Rhizocephala. In both the mouth is 

 closed and useless, and the prehensile antennae are developed ; but 

 in the Cirripedes there are eyes and some other proofs of a higher or- 

 ganisation. The pupae of the Cirripedes attach themselves, as has 

 been explained, and those of the Rhizocephala fix themselves to the 

 abdomen of common and hermit crabs. The future of the RJiizo- 

 cephaloiis pupae is wonderful, and would be perfectly unique were 

 it not for the notice given above of the Anelasma. They remain 

 through life without mouth or any digestive apparatus ; they lose 

 all their limbs completely after their metamorphosis from the pupa, 

 and appear (writes Fritz Muller) as sausage-like sac-shaped or 

 discoidal excrescences upon their victim or " host," filled with ova. 

 From the point of attachment closed tubes — ramified-like roots — 

 sink into the interior of the " host," twisting round its intestines 

 even, or becoming diffused amongst the sac-like tubes of its liver. 

 The only manifestations of life which persist in these non plus 

 tiltras in the series of retrogressively metamorphosed Crustacea 

 are powerful contractions of the roots, and an alternate expansion 

 and contraction of the body, in consequence of which water flows 

 into the blood cavity, and is again expelled through a wide orifice. 

 There is a close resemblance between the early larvae or Natiplii 

 of the Rhizocephala and the Cirripedia, and the likeness of the 

 pupae to each other has been noticed ; but then the retrograde 

 metamorphosis causes an extreme divergence of character, the 

 Anelasma linking, however, the two orders Rhizocephala and 

 Cirripedia together, and offering a strong evidence of their former 

 common origin. (Fritz Miiller, translated by W. S. Dallas.) 



Thus the Crustacea, like some of the other great divisions of 

 the Articnlata, have some kinds which do not undergo any meta- 

 morphosis, and others in which the transformation is very great 

 and progressive ; whilst a few forms positively retrograde in their 

 development during their wonderful evolution. 



