58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



nized this arrangement, and he further homologized the feeding claws 

 with the second antennae of the Crustacea and the sHme papillae with 

 the mandibles of the Crustacea, the Myriopoda, and the Insecta. Such 

 an interpretation of the third brain with its nerve connections running 

 to the feeding claws is in accord with the opinions of many authors, 

 among them being Manton (1949), Holmgren (1916), Hanstrom 

 (1935), Henry (1948), and others. 



However, Federov (1929) considers that the brain consists of the 

 prostomial archicerebrum and of postoral elements consisting of the 

 antennal centers, the premandibular centers, the mandibular centers, 

 and the papillar centers. Snodgrass says of his work, "Federov's 

 elaborate analysis of the brain structure and nerves would be more 

 convincing if it took into account the embryonic development of the 

 brain; his results are entirely unsupported by ontogenetic evidence, 

 and are mostly at variance with observations on the brain development 

 reported by other investigators." 



Pflugfelder in his study on the development of Paraperipatus am- 

 boinensis gives considerable evidence in support of Federov's idea 

 and illustrates his findings by a series of reconstructions of cross sec- 

 tions through the head region. The third or tritocerebral segment he 

 considers to be anterior to the jaw or mandibular segment, and an- 

 terior to the commissure of the jaw or mandibular segment, he finds 

 another one which he considers to be the first postoral commissure. 

 His theories have been supported by Weber (1952) who says in his 

 discussion of Henry's and Pflugfelder's papers, "It [Henry's opinion 

 that the mandibular nerve belongs to the tritocerebrum] ... is never- 

 theless erroneous and Pflugfelder refuted Miss Henry's opinions in 

 advance without having known her work published at the same time 

 as his." 



Despite these opinions of Pflugfelder that appear to support Fed- 

 erov, and Weber's acceptance of the idea that a premandibular somite 

 exists in the Onychophora, there are several factors that one must con- 

 sider before accepting Pflugfelder's work. In the first place in the 

 stages preceding the formation of the preoral cavity one may plainly 

 see that the feeding claws are the appendages of the segment immedi- 

 ately behind the antennal segment (fig. 5 A, B, C), that they are 

 adjacent to the second ventral organs, and that there is no extra 

 coelomic sac between the segments of the antennae and of the feeding 

 claws (fig. 4 D). 



It is evident that Pflugfelder used an advanced embryo of Paraperi- 

 patus amboinensis in making the series of cross sections upon which 

 he based his conclusions. The preoral cavity has formed and the feed- 



