8 HISTOEY OF CEUSTACEA. CHAP. II. 



surd and contradictory inferences, if any such were to be 

 drawn from his theory. To this want of demonstrated 

 contradictions I think we may ascribe just the same im- 

 portance in Darwin's favour, that his opponents have 

 attributed to the absence of demonstrated intermediate 

 forms between the species of the various strata of the 

 earth. Independently of the reasons which Darwin 

 gives for the preservation of such intermediate forms 

 being only exceptional, this last mentioned circumstance 

 will not be regarded as of very great significance by any 

 one who has traced the development of an animal upon 

 Iarva3 fished from the sea, and had to seek in vain for 

 months, and even years, for those transitional forms, 

 which he nevertheless knew to be swarming around him 

 in thousands. 



A few examples may show how contradictions might 

 come forth as necessary results of the Darwinian hypo- 

 theses. 



It seems to be a necessity for all crabs which remain 

 for a long time out of the water (but why is of no con- 

 sequence to us here), that air shall penetrate from behind 

 into the branchial cavity. Now these crabs, which have 

 become more or less estranged from the water, belong 

 to the most different families the Kaninidae (Banina), 

 EriphinaB (Eriphia gonagra), GrapsoidsB (Aratus, Ses- 

 arma, &c.), Ocypodidse (Gelasimus, Ocypoda), &c., and the 

 separation of these families must doubtless be referred 

 to a much earlier period than the habit of leaving the 

 water displayed by some of their members. The arrange- 

 ments connected with aerial respiration, therefore, could 



