68 University of California Publications. [zoology. 



The habit of the San Francisco colonies of S. argentea seems 

 to be controlled in an interesting fashion by gravity. The 

 branches are borne on all sides of the stems, which were fastened 

 by their bases to the perpendicular side of a shore boulder. 

 Each stem had curved upward, so that while the basal portion 

 was nearly horizontal, the terminal fourth or fifth was approxi- 

 mately vertical. In this terminal vertical portion the branches 

 and the hydrothecae on them were arranged symmetrically with 

 respect to the axis of the colony; and in this region the axis of 

 the colony and the lines of force of gravity were parallel. At 

 the base, where they were not parallel, branches and hydrothecae 

 were oriented with respect to the force of gravity alone. Both 

 hydranth and branch buds, as well as the stem, thus appear to 

 be more or less negatively geotropic, the hydranths always being 

 borne on the upper sides of the branches; the latter grow 

 obliquely away from the centre of the earth but never become 

 parallel to the main stem. 



Sertularia filicula E. & S. 



PI. IX. Fig. 80. 



Sertularia filieula, Ellis and Solander, Zooph., p. 57. Hineks, Brit. 



Hydr. Zooph., 1868, p. 264. 

 Sertularia anguina, Trask, Proe. Cal. Ac, 1854, I, p. 112. 



filicula, Clark, Proc. Ac. N. Se. Phil., 1876, XXVIII, p. 210. 

 anguina, Clark, Trans. Conn. Ac, III, p. 255. 



var. robusta, Clark, ibid., p. 256. 

 inconstans, Clark, Proe. Ac N. Sc Phil., 1876, p. 222. 



Distribution. San Diego (15-25 fath.), San Pedro, San 

 Francisco (shore rocks), Cal. Monterey to Pt. Reyes, Cal. 

 (Trask). Vancouver I. (Dawson). Nunivak I. to Shumagin 

 Is., Al. (10 fath.); San Miguel I., Cal. (Clark). Grand Manan, 

 20 fath. (Stimpson). Labrador (Packard). British shores 

 (Hineks). 



Gonothecae are present on colonies from San Francisco Bay, 

 and leave no doubt of the identity of 8. anguina and 8. filicula. 

 It is probable, as Clark suggests, that the robust variety may 

 prove to be identical with the European 8. abietina, in which 

 case the species will take the latter name. I do not agree, how- 

 ever, that the habit of S. inconstans is sufficiently distinct from 

 that of 8. filicula to cause a separation of the species. 



