FEEDING, LOCOMOTION AND RESPIRATION 27 



bears a group of brush-like setae which push the food trapped on 

 the filter forwards to the maxillules where another group of setae 

 pushes the food on to the mandibles, and so into the mouth. A 

 mechanism of this type is found in the mysidacean Gnathophausia, 

 which is a primitive representative of its group. Gnathophausia 

 swims by means of its abdominal limbs (pleopods), and uses the 



ANTENNULE LABRUM 



1ST MAXILLR 



2ND MAXILLA 



MANDIBLE 



TUBE BEARING 

 OPENING Ofi 

 EXCRETORY Ci 



Fig. 19. A, Head of Triops granarius (Notostraca). The legs on the 

 left side of the figure have been emitted, and the mandible on 

 that side pulled back to show its teeth, which are normally 

 hidden beneath the labrum. Notice that there are no antennae, 

 the functions of these organs are taken over by the prolongations 

 from the first leg. B, Trunk limb of Triops granarius, note the 

 absence of filter setae. C, Second trunk limb of Lepidocaris, 

 orientated in the same way as fig. B, with the inner border to the 

 right (C, after Scourfield, 1926). 



