MYEIAPODA. 671 



ganglia in each segment, as in most of the Annelida, Crusta- 

 cea and Insecta ; but in the vermiform Cliilognatha, which 

 former researclies have proved to me are most nearly con- 

 nected to the Annelida, the two parts of this double cord, are 

 so closely united laterally as to appear like a single cord that 

 gives off a multitude of small nervous trunks at its sides 

 throughout its whole length, but without distinct ganglionic 

 enlargements at their origin," The brain is "composed of at 

 least four pairs of ganglia." 



The digestive system comprises the long, tubular salivary 

 glands, of which two are found on each side of the oesophagus 

 and stomach, opening by a long excretory duct into the mouth ; 

 and Professor Leidy has described two others which are 

 placed on each side of the (Esophagus, and are pyriform, con- 

 glomerate, and cellular in structure. Also the long intestinal 

 canal which is much as described in the higher insects ; while, 

 as in Julus, according to Leid^', "at the termination of the 

 proventriculus, there open two biliary tubes, and from it, sui'- 

 rounding the commencement of the ventriculus, is suspended 

 a broad, white, opaque, reticulated band, apparently composed 

 like the reta adiposa of insects." 



The circulatory system is of a much lower type than in 

 insects, and in Julus it approaches, according to Newport, by 

 its rudimentary development that of the worms. The vascular 

 system consists of a dorsal vessel, or heart, with very numerous 

 separate chambers, almost equal to the segments of the body, 

 which connects with another system of vessels lying on the 

 under side of the body between the alimentary canal and the 

 nervous cord. This plexus of vessels thus forms "a vascular 

 collar around the anterior part of the alimentary canal." "At 

 each constriction of the heart in the Julldce, between two 

 chambers, there are two transverse lateral orifices, as in In- 

 sects," which Newport supposes to be either the terminations 

 of delicate veins, or simple apertures admitting the blood from 

 the venous sinuses in the body. 



The trachear^r system is much as in the six-footed insects, 

 and the stigmata have the same relative position, but are 

 placed on the alternate segments of the body. 



In the Chilopoda the sexual system is much as in the six- 



