CLASSIFICATION. ANTENNATA. 579* 



and of the gonad, the diplopody, the number of the jaws, which 

 give them strong claim to independence ; while the Opis- 

 thogoneates in the features mentioned present a distinct approx- 

 imation to Insecta, from which they principally differ in the 

 number and uniformity of the segments and in the absence of 

 a differentiated thorax and abdomen. And there would be a 

 strong case for this grouping, were it not for the Symphyla, 

 which, although progoneate and agreeing with the Pauropoda 

 in the non-correspondence of the legs and the sterna, resemble 

 Chilopods in the presence of a ventral blood-vessel, in the absence 

 of diplopody, in the width of the sternal plates, and in the arrange- 

 ment of the jaws. In fact in the latter point they may be said 

 to be more insectan than the Chilopoda. Having regard to 

 these facts, it seems unsatisfactory to place the Symphyla with 

 the Diplopoda (Chilognatha) and Pauropoda as Progoneates. 

 On the other hand it is impossible to place them with the Insecta 

 from which they differ in their progoneate condition (a feature 

 to which considerable morphological importance is attributed), 

 and in their numerous segments and in the absence of a differen- 

 tiated thorax and abdomen. The only other course open to 

 us is to retain the old group Myriapoda and to leave them in 

 it, indicating their insectan affinities by placing them next the 

 Chilopoda. This is the course we have followed in this work : 

 we have retained the class Myriapoda and divided it into four 

 orders, the Pauropoda, the Diplopoda, the Chilopoda, and the 

 Symphyla. We admit the interdigitation of these orders with 

 each other and with the class Insecta, and we think that there 

 are good reasons which would entirely justify the revival of 

 the class Antennata to include them. We do not here establish 

 such a class mainly on the grounds of convenience and recent 

 custom. If we did, we should define it as follows : Tracheates 

 with antennae, with more than one pair of jaws, with malpighian 

 tubes and definite metameric stigmata ; and we should divide it 

 into five orders, viz., Pauropoda, Diplopoda, Chilopoda, Symphyla, 

 and Insecta. 



The consideration of the Pauropoda still remains. They 

 might be united with the Diplopoda. We prefer however 

 to keep them apart, on the ground of the fewness of their seg- 

 ments, the incompleteness of their diplopody, the width of their 

 sternal plates, and the dorsal position of the testis (not of the 



