THE APODID& 



PART I 



crossing of the nerves must take place. Our own 

 examination of the nervous system quite confirmed 

 this, as shown in Figs. 19, 20, and 21. These figures 



FIG. 19. Diagram to show the derivation of the central nervous system of Apus from 

 that of a bent Annelid as in Fig. 18 ; drawn on the assumption that the nerves 

 of the first antennae of the original Annelid branched from the first ventral 

 ganglion, i, 2, 3, 4, 5, ganglia of the ist, 2nd, 3rd, 4th, and 5th segments, b, 

 brain of Annelid ; /3, of Apus ; ce\, cesophageal commissures of Annelid ; o?2, 3, 

 the two cesophageal commissures of Apus derived from ce\ ; a\> a%, nerves to the 

 ist and 2nd antennae of the Annelid ; cq, 0.0, ditto of Apus ; e\, e-2, nerves to the 

 eyes of the Annelid ; 771, rjo, ditto to those of Apus. 



should be compared with Figs. I and 2, which show 

 the positions of the antennae. 



This position of the first antennal nerve tells us, 

 however, nothing definite as to the position of the 



