478 THE AMERICAN NATURALIST [Vol. LVI 



of the five eggs and perhaps the easiest to rear. The eggs m 

 arranged according to size, depth of color and ease with ^ 

 they may be reared as follows : 



As in the case of Platynereis the essential point in rearing 

 these annelids is to give them food at just the right time in the 

 larval stage. This time varies somewhat with each form. Briefly, 

 food must not be given before the yolk and oil are wholly used 

 up. One needs but to watch the larvae, note the disappearance of 

 the oil from the gut, and then add diatoms. 



E. E. Just 



Howard Txiversity 



EEFEEEXCES 



'11. Zur Xaturgeschichte von Nereis dumerilii Aud. et Edw. Zoologica, 



Lillie, F. E. and Just, E. E. 



'13. Breeding Habits of the Heteronereis Form of Nereis limbata at 

 Woods Hole, Mass. Biol. Bull., 24. 



AN OBSERVATION ON THE "CLUSTER-FORMATION" 

 OF THE SPERMS OF CHITON ^ 

 "While engaged with an inquiry into the natural history of 

 the chitons, in 1918,^ I several times made an observation which 

 may have a bearing on the significance of sperm-clusters, and on 

 the mechanism of their formation. The matter could not at 

 the time be adequately investigated, but since I shall not soon 

 he in a position to examine it furtlier my observations are here 

 related for what they may be worth. Tlie species concerned is 

 Chiton iuhermlntus Linn., an intertidal form quite abundant at 

 Bermuda. It is necessary to note, first, certain features of the 

 breeding process, which seems to me to have heretofore been 



1 Contributions from the Bermuda Biological Station for Eesearch. No. 

 119. 



2 The corrected proof and manuscript of this article were returncil to 



