No. 2.] 



THE EMBRYOLOGY OF LIMULUS. 



251 



The result of these comparisons is sufficient, I think, to 

 justify the dismemberment of the old group Myriapoda and the 

 association of the Chilopoda with the Hexapoda in a group to 

 which the much abused term Insecta may be applied, while, 

 until more definite knowledge be obtained, the Diplopoda must 

 be allowed to stand alone. The position of the Pauropoda is 

 as yet very uncertain as we are almost entirely ignorant of their 

 internal structure. In the tendency towards a fusion of somites, 

 in the lack of a second pair of maxillae, and in the positions of 

 the external paired openings of the genital ducts at the base of 

 the second pair of ambulatory appendages they show undoubted 

 affinities with the Diplopoda; but the peculiar triramous an- 

 tennae and especially the characters of the hexapod young (if 

 Ryder's (79) figure of the young of Eurypauropus be correct) 

 militate against this view. 



The Malacopoda^ (Peripatus) are also frequently placed in 

 close association with the Myriapods, but it may be that 

 their status as members of the Arthropod phylum is not 

 beyond question. In the following points they differ from all 

 "Tracheates" and also from all Arthropods, while in just 

 these same points they show affinities with the Annelids: — 



The presence of functional nephridia in each body segment; 

 the presence of well developed coxal glands {cf. setiparous 

 glands of Annelids) ; the existence of an outer circular muscular 



1 Malacopoda, Blanchard 1847; Onychophora, Grube 1853; Protracheata, Moseley 

 1874. 



