JAPANESE PA LOT/), CERATOCEPHALE OSAWAT, X. SP. 17 



the stage (fig. 1), in which the sexual color difference could not 

 l>e perceived. As before indicated, such larger worms begin to 

 be observed from the early part of September. During the course 

 of that month the change proceeds further and the worms acquire 

 the appearance of those shown in figs. 3 and 4. Though the 

 head end remains of nearly the same size as in an early stage, 

 most of the segments in the anterior portion of the body, have 

 undergone a considerable growth ; they are now much broader 

 and more plump-looking than before, owing to the development 

 of sexual products within. That portion of the body, composed 

 of approximately one-third the total number of segments, is the 

 part which goes to make up the body of the epitoca. It is of a 

 reddish color much lighter than before, the female being distin- 

 guished by a yellowish tint which grows deeper as the days 

 advance. The posterior portion of the body, comprising about 

 two-thirds of the total number of segments, is destined shortly 

 to be cast off. It stands in contrast with the anterior part not 

 only in that its segments have remained stationery in size and 

 consequently are very much narrower, but also in the marked 

 change which has taken place in the color of that part. Here 

 the reddish color has disappeared, having given place to a dirty 

 brown on the sides and to a pale streak in the middle. The 

 dorsal vessel presents an interrupted appearance, preparatory to 

 becoming sooner or later quite imperceptible. The posterior region 

 in question is evidently undergoing a degenerating process. 



For some time, this region is seen to pass gradually into the 

 anterior epitocous region ; but as the change into the epitoca 

 nears its completion, the two regions become quite abruptly 

 demarcated (fig. 5). 



The worms represented in fig. 5 are those in which the 



