150 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Campodea rather than Diplopoda, but is unquestionably nearer Diplo- 
poda than it is to Chilopoda. 
The gnathochilarium 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 homologized 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. These homologies, however, 
simply indicate a partial parallelism in development; for in most re- 
spects Crustacea and Hexapoda are very divergent classes. 
