n STRUCTURE OF SCHIZOTARSIA 59 



from the others in being nearer to one another and forming a 

 single mass when seen by the nalced eye, though when examined 

 by the aid of a microscope we can see all the different parts are 

 there. Thirdly, the division into two cords mentioned in the 

 Chilognatha is carried to a much greater extent. The ganglia in 

 each segment can be seen plainly to be double, and the cords 

 connecting the ganglia are two in number. We can plainly see 

 that the ventral nervous system of the Chilopoda consists of two 

 cords lying parallel to one another, and each having a ganglionic 

 enlargement in every segment. "Whether a visceral nervous 

 system is present in the group is doubtful. 



The eighth family of the Chilognatha, the Polyxenidae, show 

 an approach to the Chilopod nervous system. 



The generative system differs chiefly in the opening of the 

 genital apparatus at the end of the body instead of in the third 

 segment ; though this difference only separates the Order from 

 the Chilognatha and not from the other Orders. They also have 

 two pairs of large accessory glands (as they are called) connected 

 with the genital openings. 



Order III. Schizotarsia. 



The third Order of Myriapods, the Schizotarsia, show a much 

 greater resemblance to the Chilopoda than to the first Order, the 

 Chilognatha. There are, however, important differences to dis- 

 tinguish them from all the other Orders. 



The shape of the body is short, thick, and very compact. The 

 composition of the individual segments resembles that found in 

 Chilopoda rather than that of Chilognatha. 



The antennae are very long, longer than in any of the 

 Chilopods, and are composed of a great number of very small 

 joints. The mouth parts show a greater length and slenderness 

 than do those of the other Orders mentioned as yet. They con- 

 sist of — 



1. An upper lip partly free, but fused at the sides with the 



rest of the head. The upper lip is in three parts, as in 

 the Chilopoda, but with the middle part very small and 

 the lateral pieces large. 



2. A pair oi jaws or mandibles. These are provided not only 



with teeth, as in the other Myriapods, but also with a 

 sort of comb of stiff bristles. 



