NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA — SNODGRASS 5 1 



part of the trunk, however, forms a cephaHc lobe (D, E) bearing 

 the antennae, a pair of small dorsal eyes (E, E) just behind the 

 antennal bases, and on the ventral surface the mouth (D). The 

 mouth, which is a triangular opening into the stomodaeum, is sunken 

 into a preoral cavity surrounded by an integumental circumoral fold 





Fig. 21. — Onychophora, ancient and modern. 



A, Peripatoides novac-zcalandiac Hutton. B, Ayshcaia pcdunculata Walcott 

 (191 1), of Middle Cambrian, British Columbia, "conjectural restoration" (from 

 Hutchinson, 1930). C, Xemision aucrszualdi Pompeckj (1927), of Algonkian, 

 proterozoic pre-Cambrian (from Heymons, 1928, broken lines hypothetically 

 completing larking parts). D, Peripatoides noz>ac-zeaIandiac, anterior part of 

 trunk, ventral view. E, same, head and anterior part of body, lateral view. 

 F, same, right jaw, dorsal view, with muscles. 



a-d, jaw muscles; Ant, antenna; Ap, apodeme of jaw muscles; cof, circumoral 

 fold; E, eye; /, jaw; iL, first leg; Lm, labrum; OP, oral papilla. 



(cof). Within the preoral cavity is a small anterior labral lobe 

 (Lin), and a pair of flat, two-hooked jaws (/) that converge pos- 

 teriorly at the sides of the mouth. On the sides of the head, laterad 

 of the mouth, is a pair of oral papillae (E, D, Op) that give vent 

 to a pair of large, many-branched slime glands widely spread in the 



