METAZOA INSECTA. 391 



ogous with the second pair of maxillae and the first pair 

 of maxillipeds in Crustacea. 



The view that the head is made up of seven segments 

 is strengthened by the fact that seven ganglia are found 

 in the cephalic region of the embryo. Since the pre- 

 mandibular and superlingual appendages are either 

 embryonic or difficult to detect as compared with the 

 mandibles and maxillae, we will consider only these latter 

 organs in this general treatment of insects. 



The middle region or thorax of Campodea (see PI. 945, 

 fig. i) is made of three distinct and movable segments 

 named respectively the prothorax, mesothorax. and meta- 

 thorax. The posterior region or abdomen is composed 

 of ten segments, likewise distinct and freely movable. 



The body is hairy and is without scales or feathers ; 

 it extends longitudinally and there is little concentration 

 of parts. The junction of the head with the thorax is a 

 soft unchitinized portion of the body wall which forms a 

 functional neck, while the junction of the thorax with the 

 abdomen is nearly as broad as the body itself, and for 

 this reason the abdomen is said to be sessile. 



The head is without eyes according to Westwood, 

 Meinert, Lubbock, and Oudemans, while Nicolet and 

 Grassi state that they are present. 1 



The appendages like the body are primitive in most of 

 their characteristics. The head is provided with a pair 

 of long, hairy ante'nnae (Pi. 945, fig. i) and with three 

 pairs of distinct mouth parts. These latter organs are 

 the hollow mandibles (PI. 946, fig. 2, one mandible with 

 the muscles that move it ; fig. 3, the tip of the mandible 

 enlarged), first pair of maxillae (fig. 4, showing the inner 

 lobe, (^/), of the right maxilla, and the outer lobe, (<?), 

 with its palpus (/"), of the left maxilla ; the lingua, 



1 On this subject see, Vire, Le Campodea staphylinus Westwood, 

 et ses varietes cavernicoles ; Bull. Mus. d' Hist. Nat. Paris, 1897, 

 no. 3. 



