392 SYNOPTIC COLLECTION. 



hypopharynx, or tongue, (/), is seen in the median line, 

 drawn without the supporting chitinous frame-work), and 

 the second pair of maxillae or labium (fig. i, /; palpus 

 of same enlarged in fig. 5). 1 Comparatively speaking, 

 these mouth parts are but slightly differentiated, since 

 Campodea feeds upon soft substances and has no need 

 of hard, specialized mouth organs. They are set in mus- 

 cles (some of which are seen in PL 946, fig. 2) within 

 the cavity of the skull, like those of Scolopendrella, and 

 may be used for either biting or sucking, although they 

 are more allied to the biting type. They are, in fact, 

 generalized structures and are probably similar to those 

 that gave rise to the complicated organs for cutting, pierc- 

 ing, and sucking of the more specialized insects. This 

 view is strengthened by the fact that the mouth parts of 

 Neanura, one of the Thysanura of the suborder Collembola, 

 have become modified into suctorial organs. 2 



The three pairs of legs attached to the thorax (PI. 945, 

 fig. i) are well developed and similar in structure, since 

 they are all used in running. They are jointed and pro- 

 vided at their ends with two tiny hooks for taking hold of 

 objects. These legs are the only appendages of the 

 thorax and, furthermore, there are no vestiges or indica- 

 tions of any kind that the Campodea or the Thysanura 

 ever possessed appendages in the form of wings. This 

 is one of the important reasons why the group is entitled 

 to the position of the most primitive order of insects. 



According to Uzel the embryonic Campodea has ten 

 distinct abdominal segments of which the first nine are 

 provided with appendages. In the adult each of the first 



1 According to Uzel these are not the labial palpi but the outer 

 lobes of the labium This author differs from Meinert in his inter- 

 pretation of the other parts of the second pair of maxillae (see Zool. 

 Anz., XX, 1897, p. 234). 



2 Folsom, The Anatomy and Physiology of the Mouth Parts cf 

 the Collembolan, Orchesella cincta L. ; Bull. Mus. Comp. Zool., 

 XXXV, no. 2, 1899, p. 35. 



