476 THE AMERICAN NATURALIST [Vol. LVI 



stated, however, that on this point the observations so far made 

 are not conclusive. In order to determine fully that the eggs laid 

 by worms in the cultures in the laboratory are from the same 

 worms started in the culture and not from an intermediate form 

 and are the only eggs laid, it would be necessary to make continu- 

 ous observations on isolated worms. So far it has not been 

 feasible to do this, since it would mean practically continuous 

 residence at Woods Hole through the winter. 



TABLE I 



On the other hand, it is just barely possible that in a state of 

 nature the life history is more complex than in the laboratory 

 cultures. Under operation of changes in such factors as density 

 of the sea-water, food, and temperature, the life history of the 

 worms may be modified. That this possibility deserves some con- 

 sideration we may conclude from the sex ratio, if such meagre 

 data will allow. In tli.- laboratory cultures females appeared first 



just the revers.' is true. 



Whatever our conrlusioiis as to tlw interpretation of these ob- 

 servations, it seems to the writer that the life history of this 

 interesting nereid is worthy of further studv. 



