444 



NATURAL SCIENCE. 



Dec. 



lays special stress upon the position of the genital opening. The 

 Diplopoda and Pauropoda (in which this opening occurs in the anterior 

 region of the body) are classed by him as Progoneata, in opposition to 

 the Chilopoda, Symphyla,^ and Hexapoda, in which the generative 

 duct opens at the hinder end of the animal, and which are accordingly 

 called Opisthogoneata. 



Mr. Kingsley reviews the main pointsof structure of the Diplopods, 



F!g. 5i 



atf' ,.". St 





^mjn 



iM^^- -1^'-5&J. ..:>:>■ 



ant. '^[f\iK ff\ 



4' 'f '-'M 



Fig. 4. Si;, 







pt ,^' 



mst'' 

 mtt. ^ 



issii 



X-l 



Fig. 8. 



Figs. 5-7. — Embryos of Xiphidlum. cm. embryo, in. indusium. in', furthest 

 extension of indusium. Fig. 4. — Young embryo ol Xiphidium. Fig. 8. — 

 Embryo of Annrida. ind. indusium. mp. micropyle. p.cl. procephalic 

 lobes, m. mouth. I. labrum. ant. antennae, tc. tritocerebral appendage. 

 ind. mandibles, mx^. mx^. maxillas i and 2. pt., mst., mtt. thoracic 

 segments, an. anus. [After Wheeler.] 



Chilopods, and true Insects, and finds further support for the associa- 

 tion of the two latter groups in opposition to the former, in the 

 correspondence of the pairs of jaws in centipedes and insects, 

 and the coalescence of the somites in pairs in the millipedes. The 

 systematic position of the Pauropoda, Pycnogonida, Trilobites, 

 Tardigrada, and Malacopoda (Perlpatus) is considered uncertain by 



^ According to some observers, however, the genital opening in the Symphyla 

 (Scolopendrella) is situated in the fourth body-segment. Nevertheless, these animals 

 must be nearly related both to the Chilopoda and the Thysanura. 



