398 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



and the second the presence of distinct longitudinal striae, or furrows, on the 

 hypocone of each zooid. The first distinction is not a valid one, since the 

 nematocysts Avere intentionally omitted from the original drawing with most 

 other internal structures. Each individual of this genus found in the waters 

 of the San Diego region is provided with these distinctive organelles. The 

 second distinction, namely, the surface markings on the hypocone (fig. F, 1), 

 clearly marks this species off from P. schwartzi, which is also present in the 

 Avaters of San Diego. In other respects these two species aj^pear to be nearly 

 identical, and the final critical disciission of their status awaits a reinvestigation 

 of the Pacific species, if such it be. 



Key to Species of Polykrikos 



1. Surface of hypocone of each zooid deeply ribbed, girdle displaced one-fifth length of body .... 



kofoidi Chatton 



2. Surface of hypocone smooth, girdle without displacement schwartzi Biitsehli 



Polykrikos kofoidi Chatton 



Plate 4, figure 47 ; text figure F, 1 



Polykrikos schivartzi, Kofoid (1907&), in part, pp. 291-293, fig. 1. 

 P. kofoidi Chatton (1914c), p. 161. 



Diagnosis. — This is a colonial foi-m of 2.4, 8, or 16 individuals in chain, 

 each indiA'idual rather small in size, its length about 0.43 transdiameter ; girdle 

 submedian, displaced 0.15 transdiameter; sulcus extending length of body; sur- 

 face of hA^ioeone ribbed ; nematocysts present ; color, greenish grey to rosy. 

 Leng-th of chain of 4 zooids, 110m. .Pacific off La Jolla, California, June to 

 August. 



Description. — The individual zooids are small in size, rotund, nearly circular in cross-section, 

 or slightly dorsoventrally depressed with a length of about 0.43 transdiameter. The epicone 

 and hypocone are subequal in size with a tendency towards a slight decrease in the relative size 

 of the epicone. The chain of two, four, or eight zooids presents a barrel-shaped appearance 

 with broadly rounded apices, somewhat constricted at the girdles and the points of separation of 

 the dilferent zooids. The girdle of each zooid is submedian or slightly premedian in position. 

 It follows a nearly transverse direction around the body with a slight posterior deflection of 

 the distal end, resulting in a displacement of about 0.15 transdiameter. The furrow has a width 

 of about 0.03 transdiameter and is deeply impressed, the excavation having a slight anterior 

 extension, deeply undercutting the anterior border and gradually rounding out to the posterior 

 one. The anterior lip is usually smooth and the posterior one often thrown into undulations 

 similar to those on the surface of the hypocone. 



The sulcus forms a continuous furrow on the ventral face of tlie chain of zooids, extending 

 in a slightly sinuous line from near the apex of the first zooid to the antapex of the last one. 

 Its width is about half that of the girdles, enlarging slightly at the points of union with the 

 girdles and usually at place of union of the different zooids. At the antapex of the posterior 

 zoofd its sides become widely deflected, forming a wide, shallow notch on the ventral face. The 

 anterior flagellar pores open at the proximal junctions of the girdles and sulcus, the posterior 



