No. 2.] STOLONIZATIOX IN AUTOLYTUS VARIANS. 28 1 



pare well in size with those of the preceding stolon, thus making 

 the outline of the stolon appear somewhat wedge-shaped. The 

 parapodia and dorsal cirri in the anterior half of the body are 

 well developed, while those in the posterior half are progress- 

 ively smaller from before backward as far as the pre-anal seg- 

 ment, which segment, as in the preceding stolon, represents 

 the region of youngest growth. In this and the two preceding 

 segments, in a progressively less degree however, the parapodia 

 are quite rudimentary, and the segments present an appearance 

 very similar to the parapodia-bearing segments of stolon A. 

 The anal segment has also increased in size, and the caudal 

 cirri have been considerably elongated. In this figure the 

 segment is almost completely hidden by the head of the 

 succeeding stolon. 



In comparing the setigerous segments of this stolon with 

 those of the preceding, it will be noticed that parapodia, either 

 well developed or rudimentary, are present on all the segments 

 of the stolon except the anal. This would indicate that the 

 purely embryonic growth, as represented in the embryonic 

 segments of the preceding stolon, had passed its stage of 

 greatest activity and is not as prominent as in the preced- 

 ing stolon, the stolon having already attained a considerable 

 length and the addition of new segments from this stage on 

 progressing very much slower. 



The head of this stolon has also advanced considerably, both 

 in size and in the development of new structure. Its antero- 

 posterior diameter has increased sufficiently to equal that of 

 one of the most advanced setigerous segments of the stolon. 

 The lobed structures, appearing in the preceding stolon and 

 becoming more prominent in intermediate stages, have given 

 rise to the rudimentary anterior lateral tentacles (a.l). These 

 tentacles are thick and knob-like in structure and are directed 

 forward and outward. The dorsal median tentacle {d.vi) has 

 also appeared in the form of a slender tentacle, extending as 

 far back as the second setigerous segment. Two eyes {c.a) 

 have appeared, and have in this individual already attained a 

 considerable size. These are located at the base of the lateral 

 tentacles, and hence correspond to the anterior eyes of the 



