NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA SNODGRASS IO3 



followed directly by the mandibular (Md) and two maxillary somites 

 (Mx, Pmx), there being no evidence of a tritocerebral somite. In 

 sections the cephalic lobes show internally a distinct division into a 

 protocerebral rudiment (D, Per) and a deutocerebral rudiment (Dcr), 

 each later accompanied by a coelomic sac. It would seem to be in- 

 ferred from Pflugfelder's description, though not so stated, that the 

 primary antennal ganglia lie in the postoral "antennal somite" (Ant), 

 and yet he says, "das Deutocerebrum tritt sehr f riih mit den Antennen 

 in Verbindung durch den Antennennerv," and he clearly shows the 

 antennal nerve connection with the preoral deutocerebrum (B, 



Mth 



Fig. 44 G. — Germ band of a diplopod, Archispirostreptus gigas Peters, show- 

 ing rudiments of appendages and ganglia. (From Silvestri, 1933.) 



An. anus; Ant, antenna; AntGiig, antennal ganglion; iL, first leg; Md, mandi- 

 ble ; MdGng, mandibular ganglion ; Mth, mouth ; Per, protocerebrum ; TcrGng, 

 tritocerebral ganglion. 



AntNv). The anatomical evidence here would seem to show that 

 the true morphological relations of the antennae are with the deuto- 

 cerebral ganglia, and we can only suppose, therefore, as in the case 

 of Robinson's account of Archispirostreptus, that the postoral so- 

 called "antennal" ganglia are the tritocerebral ganglia. In any event, 

 the implication from Pflugfelder's statements that the antennae are 

 appendages of a postoral somite, but are finally innervated from the 

 preoral deutocerebrum gives the impression that there is some error 

 involved. 



The interpretation of the anterior cephalic ganglia of the diplopod 

 embryo given by Silvestri (1933), illustrated in Archispirostreptus 

 gigas (fig. 44 G), unquestionably presents the most reasonable view 



