150 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Campodea rather than Diplopoda, but is unquestionably nearer Diplo- 

 poda than it is to Chilopoda. 



The guathochilarium of Diplopoda may be homologized with the 

 appendages of three hexapod somites, but only two embryonic segments 

 have as yet been found ; and the subject needs further investigation. 



The mouth-parts of Chilopoda may be homoloirized with those of 

 insects in only the broadest way, the correspondences being principally 

 those of position. 



Between decapod Crustacea and Apterygota there are decided mor- 

 phological resemblances. The seven cephalic somites which I have 

 found in the latter group I have homologized in detail with the anterior 

 seven of the former, and pointed out that most of the homologous ap- 

 pendages function alike in the two groups. Tliese homologies, however, 

 simply indicate a partial parallelism in development ; for in most re- 

 spects Crustacea and Hexapoda are very divergent classes. 



