786 



THE AMERICAN NATURALIST. [Vol. XXXVIII. 



Lankester thoui^ht that in this form the antennae of the adult 

 were innervated from suboesophageal gangha. Though this has 

 proven to be incorrect, Pelseneer ('85) has 

 shown that the antennal gangha of the adult, 

 though associated with, are histologically per- 

 fectly distinct from those of the archicere- 

 brum, and that they are perfectly homologous 

 with the ganglia of the ventral cord. 



By the end of the ninth day there are to be 

 seen, in addition to the antennal rudiments, 

 those of the thoracic appendages, which are 

 distinctly outlined, while those of the mouth- 

 parts are merely indicated. This is the stage 

 figured by Wheeler ('89, Fig. 44). Wheeler 

 found that in many embryos, as in the one 

 which he figures, " one or, more rarely, both 

 antennary lobes are temporarily bilobed." 

 This he thought might be due to a tem- 

 porary reversion, ' tending to show that the 

 antennary lobes originally gave rise to two 

 pail s ot ai)pen(lagcs which were perhaps homologous with the 

 t\M' i)aiis ot antenna: in the Crustacea.' In embryos but 

 ^li.^hll\ more advanced I, also, have seen indications of this 

 I'llobulation Helieving that the antennai of insects are not to 

 he liomolo-izcd with tho.se ot the annelids but, rather, are 

 h"ni()(l\nani<)u.s with the other ai)pendages, I .should regard 

 tills tcnipoianly bilobed condition as a i)ossible reversion toward 

 <' 1)11 anions condition ot the a])pfndage. 



1 lu iu-\t notable change is the ap[)earance, during the tenth 

 da\. ot the mouth and ot the rudiment ot" the i)rocei)halon. The 

 moutli i> n()i Hu agmated Irom within the latter, but, as is shown 



llu'ie has bten mueh discussion concerning the origin of 

 t nuhnient ot the pioeephalon which, by many, is spoken of 

 HKulx that ot the labrum. A number of observers have 



