250 ON ANNELIDS FROM THE N.E. PACIFIC. 
Text-fig. 7, A, B, will help to elucidate the foregoing explana- 
tion of the homologies of the cephalic region in the two types. 
Conclusion.—According to the foregoing reasoning, Micronereis 
should be regarded as a more or less unaltered representative of 
a primitive ancestral form of the Nereide. - It does not appear 
to me that the features of Aficronereis can be regarded with as 
much probability as degenerations from the more highly developed 
type. 
I have set forth these views of the facts with some difhdence, 
owing to my studies having been mainly confined to the single 
family, the Nereide. A wider knowledge of the nereidiform 
group of the Polycheta might perhaps produce an alteration 
of them. 
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