340 ARTICULATA : INSECTA. 



as a hexapodous insect degraded, wingless; and partially 

 decephalized." Packard. They naturally divide into 

 three Sub-orders : 



1. ARANEINA or Spiders proper ; witli cephalo-thorax and abdo- 



men distinctly marked as two regions, and connected together 

 by a slender pedicel ; the abdomen without segments ; the 

 palpi or modified maxillse resembling shorter legs ; the man- 

 dibles ending in a hook ; and the hind part of the body pro- 

 vided with a silk-spinning apparatus. 



2. PEDIPALPI or Scorpions ; with the abdomen, in the best rep- 



resentatives, distinctly divided into segments ; and with the 

 maxillary palpi greatly enlarged. 



3. ACARINA or Mites ; with the body oval or rounded, and with- 



out apparent regions ; no wings ; no segments, the cephalo- 

 thorax and abdomen being merged into one piece. 



1. THE SUB-ORDER OF ARANEIXA or Spiders proper, are 

 the best representatives of the Arachnids, and their won- 

 derful structure, and, if possible, still more wonderful 

 habits, have engaged the attention of observers from very 

 early times. 



Their body exhibits two well-marked regions, and the 

 more or less oval or rounded abdomen is connected with 

 the cephalo-thorax by a pedicel. The abdomen is not 



members to the uses or purposes of the head." Professor Dana regards 

 1lie degree of cephalization as indicating the relative rank of the animal. 



Other things being equal, the highest degree of cephalization is exhibited 

 in those species which have the posterior extremity abbreviated that is, 

 not lengthened out and the anterior part of the body most compacted, and 

 the parts most completely subservient to the head. 



Cephalization reaches its highest expression in Man. The Mammalia as a 

 whole exhibit a high degree of cephalizntion. The Fishes a low degree. 

 The Carnivora are more highly cephnlized than the Herbivora. The Insccta 

 are more highly oephalizod tlian the Crustacea. The Crabs more highly 

 than the Lobsters, Craw-fishes, and Shrimps. And the Cephalopoda and 

 Gasteropoda are more highly cephalizcd than the Acephela. See Professor 

 Dana's learned Papers on Cephalization. 



