lOO CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



the head 5 mm. In the other specimens about this propor- 

 tion was maintained. 



The Base. — According to the description given by 

 Fewkes, the stalk of Ascorhiza was directly connected with 

 the seaweed upon which he found it growing, i. e., without 

 the intervention of a foot disc. The Catalina specimens, 

 however, indicate that the colony rises from a thin incrust- 

 ing layer composed of a number of zooecia immersed in a 

 gelatinous matrix (fig. 1, b.). A portion of the stalk {stk.) 

 with a part of the base {b.) very much magnified is repre- 

 sented in fig. 2. The outlines of the partially immersed 

 zooecia {z.) are plainly discernible. Although no polypides 

 can be distinguished, the zooecia being filled with granular 

 material, and being partially covered with debris, the septa 

 are well marked, and the shape of the zooecia corresponds 

 with those of the capitulum (figs. 2 and 3). Since the 

 specimens were disconnected when they were studied, it is 

 not known whether or not the incrusting layer is continuous 

 from stalk to stalk. On the evidence of one collector the 

 basal portion was not continuous in those specimens which 

 he obtained, but the colonies grew quite far apart on the 

 surface of a stone. A second lot was found, however, by 

 another collector, all the specimens of which were growing 

 close together on a broken shell. None of the youngest 

 stages were obtained, which would show the process by 

 which Ascorhiza passes from a horizontal to an upright 

 position. But it seems extremely probable that when the 

 incrusting portion is young its zooecia contain active poly- 

 pides which continue to function until those of the head are 

 advanced enough to carry on the work of nutrition. 



The Stalk arises from the basal portion, and consists of 

 an external layer, or cuticle, and an internal layer of muscle 

 plates, or " blocks," as they are designated by Fewkes. 

 Fig. 2 shows that the ectocyst of the stalk is a direct con- 

 tinuation of that of the base. This outer layer, or cuticle, 

 is tough and resistant. It is very transparent, and is deeply 

 constricted at regular intervals, the constrictions marking 

 more or less perfectly the muscular segmentation of the stalk. 



