73 



The presence of maxillulse in tlic Collembola is a 

 primitive feature wliieli is shared with the Symphyhx and 

 Diplopoda ; these mouth-parts are the representatives of 

 the Crustacean first maxillae {^vide Table on p. 74). 

 Furthermore, the occurrence of embryonic tritocerebral 

 appendages — the homologues of the Crustacean second 

 antennae, is also a primitive character which they only 

 share with the Thysanura. 



In the general structure of the ovary, and the absence 

 of follicles, the Collembola, as Claypole has pointed out, 

 resemble the Myriapoda more closely than the Thysanura, 

 and come nearer 'to Scolopendrella than any other type. 

 An additional Myriapod feature is perhaps seen in the 

 post-antennal organs, which are peculiar to the Collembola 

 among Insecta. They are regarded by Willem as being 

 homologous with Tomosovary's organs in Myriapods, and 

 the recent researches of Hennings* and Hallert support 

 that conclusion. 



In addition to the above mentioned characters, there 

 are a number of generalised features which suggest that the 

 Collembola are primitive animals. The most important 

 are : — (1) The extremely simple condition of the spiracles 

 where they are present ; as AVillem has pointed out, they 

 are nothing more than mere stigmatic crypts, and are to 

 all appearances similar to those of Peripatus. (2) The 

 nature of the digestive system, which is a perfectly 

 straight canal passing from the mouth to the anus 

 without ^Jresenting any convolutions. (3) The absence of 

 any external genital armature. (4) The relatively simple 

 nature of the eyes, each of which may be compared to a 

 single ommatidium of a compound eye. 



Side by side with these generalised characters, 



* Zeitschr. f. iciss. ZuoL, 7(J, lyOi, p. -2.6. 

 t Arch. f. itiiJ;. Anat., C5, 1905, p. 181. 



