SEGMENTATION OF CERTAIN POLYOH^TES. 537 



another on the ventral surface, so that a condition somewhat 

 similar to that in most specimens of Amphinome rostrata 

 obtains. 



I had not noticed spiral segmentation in any other family 

 of Chsetopods before the publication of Cori's paper (except 

 for a doubtful case of it in a Sabellid, which I shall have to 

 refer to later on). Seeing that he found it in such a different 

 group as the earthworms (and apparently it was only in earth- 

 worms that he found the spirals), I thought it would be 

 worth while to look through the specimens I had of other 

 families, and those in the Zoological Museum of this College, 

 paying especial attention to the segmentation. Although I 

 did not look through by any means all the specimens in my 

 charge, I looked through a fairly large number, and I looked 

 through almost all the specimens in the Zoological Museum 

 here. The result was curious : only in two species out of the 

 many examined did I find spiral segmentation again, but in 

 these two species it was more common even than in the genus 

 Amphinome (taking it as a whole) ; and not only was the 

 proportion of individuals that had this kind of segmentation 

 very great, but also the number of spirals in each individual 

 was most striking. 



There are six specimens of Lumbriconereis impatiens, 

 sent from Naples, in the Zoological Museum here. Of these, 

 two (young ones) seem to be regularly segmented throughout; 

 the other four (one young one) have spirals of different lengths, 

 as seen in the following table : 



1 This is a true spiral, though a short one, and not an intercalated half- 

 segment, for the furrow has a spiral course (see fig. 7). The same holds for 

 the three quarters of a round in spec. 4. 



VOL. XIXIV, PART IV. — NEW SEE. N N 



