NO. 4 HARTMAN : SPIONIDAE FROM CALIFORNIA 303 



plied with a matrix in which adults had been present, the young settled 

 and built tubes. During the spring months of 1938 similar larvae were 

 frequently encountered in the plankton, especially over areas where adults 

 were known to occur. 



In a young (4-segmented) larva there is slight trace of dark pigment, 

 at the anterior end of the prostomium and anal ring. There are as yet no 

 dorsal melanophores such as in later stages. Eyes are irregular in shape 

 and number, forming a transverse band of 4 to 8 spots along the dorsal 

 side of the prototroch. Capillaiy setae are long, limited to the first 3 seg- 

 ments, those of the first longest, extending distally beyond the body. The 

 prostomium is strongly ciliated. The ventral lobes at the anterior margin 

 of the mouth have numerous short cilia, continued in the pharynx. The 

 peristomium is recognizable as a pair of pouches at the sides of the outer 

 pair of eyes. A pair of thick ridges posterior to the lateral eyes are the 

 palpal rudiments. 



In capsules where cannibalism occurs, the larger individuals gradually 

 and effectively not only ingest blastulae but attack younger larvae and 

 devour them. In some tubes examined, it was found that all cocoons 

 were of this kind. Whether this fact was due to an inherent trait or to 

 physical conditions has not been ascertained. The more robust larvae 

 continue to develop at the expense of other capsular contents, adding 

 segments posteriorly, far beyond the 3-segmented stage, to the 12- or 15- 

 segmented one. They remain relatively quiescent, perhaps because of their 

 greatly extended condition. Like their relatives in the plankton, they have 

 dorsal melanophores in a similar pattern and deeply pigmented eyespots 

 (pi. 46, fig. 26). It is not unlikely that when escape is finally accom- 

 plished, they settle without entering the plankton. 



Three to 15-segmented planktonic larvae of this species are common 

 elements in plankton in spring. They are recognizable by a complex of 

 characters distinguishing them from other spionid larvae. The prostomium 

 is broad, truncate in front, with eyespots approximately in crescentic 

 arrangement. Each segment has a medially placed, black spot on the 

 dorsal side. These are broad, dendritically branched on the first 6 seg- 

 ments, diminishing in size thereafter (pi. 47, fig. 34). They are capable 

 of expansion and contraction. During larval life the long capillary setae 

 are replaced by thicker limbate setae in the first 4 setigerous segments, 

 and from the postmodified (fifth) segment to the anal end. The modified 

 fifth has typically 2 pairs of stout spines on either side, resembling those 

 in the adult but much smaller (pi. 47, fig. 36). Palpi are short, thick, 



