NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA SNODGRASS 59 



The small posterior lobes of the brain from which arise the posterior 

 stomodaeal nerves (fig. 25 B, i), together with the adjoining parts 

 of the nerve cords that give off the nerves of the jaws (A, B, C, /), 

 are said by Evans to be secondarily added to the antenno-ocular lobes 

 from the ventral organs of the postoral jaw somite (fig. 23 B, 2V O), 

 and Kennel clearly shows in a head section (fig. 27 A) the inclusion 

 in the brain of a mass of neural cells given off from these generative 

 centers (2VO). The definitive onychophoran brain, therefore, as 



Si: Con 



Fig. 26. — Internal structure of the brain of Peripatopsis capensis Grube. 

 (From Holmgren, 1916.) 



AntCom, antennal commissure; AntGlm, antennal glomeruli; AntNv, sensory 

 antenna! nerve ; AntT, antennal tract ; b, motor nerves of antenna ; Cc, corpus 

 centrale ; e, nerve to circumoral fold ; /, median dorsal nerve ; Gb, globuli of 

 corpus pedunculatum ; ;, stomodaeal nerves; ;', nerve of jaw; OpNv, optic nerve; 

 Fed, peduncle of corpus pedunculatum ; StCon, stomodaeal connective. 



shown by the records of its development, and as claimed by Holmgren 

 (1916) and by Hanstrom (1928, 1935) from histological evidence, 

 would appear to be a syncerebrum composed of a prostomial fore- 

 brain including the ocular and antennal centers, and of a postoral 

 hindbrain containing the centers of the posterior stomodaeal nerves 

 and the nerves of the jaw appendages. 



A quite different concept of the composition of the onychophoran 

 brain is deduced by Fedorow (1929) from a study of Peripatus 

 tholloni, in which he attempts to correlate the cerebral nerves with 

 the nerves of a series of body segments (fig. 24 A, B). Fedorow 



