520 



ZOOLOGY 



SECT. 



dorsal, ventral, or lateral regions contract, the abdomen will be 

 raised, lowered, or turned sideways. In the limb-bearing portion 



^._ of the abdomen and in the 

 thorax there is no longer a 

 continuous muscular tube, 

 but paired dorsal (dm.) and 

 ventral bands, which pass 

 respectively above and below 

 the origins of the limbs : the 

 dorsal bands arise in front 

 from the head-region, the 

 ventral from a strong fibrous 

 plate, the cephalic apodeme 

 (c. ap.), lying just behind the 

 gullet. 



Each appendage is moved 

 as a whole by muscles pass- 

 ing into it from the trunk : 

 its various parts are acted 

 upon by delicate muscular 

 slips running to the various 

 podomeres of the axis and 

 to the endites, thus render- 

 ing them separately movable. 

 The only example we have 

 yet met with of appendages 

 moved by definite muscular 

 bands is that of the curious 

 Rotifer Pedalion (p. 323). 

 The muscles are all striped, 

 a character which applies to 

 the Arthropoda generally, 

 with the exception of the 

 Onychophora. 



Digestive Organs. 

 The mouth (Fig. 431, mth.) 

 is situated on the ventral 

 surface of the head, and is 

 bounded in front by the 

 labrum (Ibr.), on each side 

 by the mandibles, and be- 

 hind by the paragnatha. 

 The food appears to be 

 pushed forwards towards 

 the mouth by the toothed 

 bases of the thoracic feet, and is broken up by the mandibles, which 

 work laterally. The maxillaB are probably functionless, or nearly so. 



