SOME OBSERVATIONS ON ASCORHIZA OCCI- 



DENTALIS FEWKES, AND RELATED 



ALCYONIDIA. 



BY ALICE ROBERTSON. 



Plate XIV. 



In a paper entitled "New Invertebrata from the Coast 

 of California," published in the Bulletin of the Essex Insti- 

 tute, Vol. XXI, 1889, Dr. J. Walter Fewkes describes a 

 new and extremely interesting Bryozoan, Ascorhiza occi- 

 denialis, which had been dredged in the channel between 

 Santa Barbara and Santa Cruz Island. The description, 

 though full of interest, was admittedly deficient in some 

 important points, and the writer was unable to arrive at 

 definite conclusions in regard to the relationships of this 

 curious Bryozoan. Since the publication of Dr. Fewkes' 

 article in 1889, nothing farther had been learned of Asco- 

 rhiza until last summer, when several fine specimens were 

 obtained at the Marine Biological Station of the University 

 of California at San Pedro. A study of this new material 

 has served to complete the description of this interesting 

 species and to establish its relationships. 



These specimens of Ascorhiza were dredged in forty-five 

 fathoms off Santa Catalina Island, on the coast of California. 

 This form is unique among the Bryozoa in having the 

 major part of the colony elevated upon a segmented muscu- 

 lar stalk. The whole colony consists of a head, or capitu- 

 lum, a stalk, and a basal portion by which it adheres to 

 some foreign body. Fig. i represents such a colony, and 

 shows the extremely flexible character of the stalk. Some 

 of the specimens lacked the basal portion, the stem having 

 evidently been broken off some distance above it. There 

 is considerable variation in the height of the various speci- 

 mens, but the relative heights of stalk and capitulum are 

 about as five to one. Thus, in one perfect specimen, the 

 stalk measured 10 mm., the head, 2 mm. In another, which 

 had been torn from its substratum, the stalk is 23 mm. long, 



[ 99 ] March ii, 1902. 



