vol. i.i Torrey. — Hydroida of the Pacific Coast. 35 



spherical with small spadix; female smaller, slightly elongated, with dis- 

 tally extended spadix, and containing one, or at most, two eggs. 



Distribution. San Francisco Entrance; Tomales Bay, CaL 



This hydroid grows commonly in patches sometimes several 

 square inches in extent on rocks exposed to the breakers of the 

 open sea, between tidal limits. The color of the hydranth and 

 male gonophore is a very delicate pink ; the female gonophores 

 are of a faint orange due mainly to the yolk in the egg. The 

 perisarc of the hydrophyton is of a dark horn color. Each 

 gonophore has a separate origin from the fertile hydranth. 

 I have never seen more than four on the same hydranth. 



This species is readily distinguished from the eastern H. 

 polyclina and European H. echinata by the tentacles on the 

 fertile hydranths, the smooth tubular processes from the hydro- 

 rhiza, and the small number of eggs in the female gonophore. 

 The sterile hydranths are much stouter than those of H. poly- 

 clina, with which I have compared them. The species is related 

 closely to the Stylactis fusicola (Sars) of Allman. The latter 

 has all the characters of Hydractinia save the spiral zooids and 

 the coenosarcal covering of the hydrorhiza — both of which char- 

 acters might have been easily overlooked. Sars originally 

 described the species as a Podocoryne, from which genus it is 

 excluded by the possession of fixed sporosacs. I feel, however, 

 that Allman was hardly justified in removing it to his genus 

 Stylactis. 



The arrangement of tentacles in series of four each is of 

 considerable interest. These series evidently represent succes- 

 sive generations of tentacles — though four do not appear simul- 

 taneously in all cases at least, since at the edge of a colony 

 young hydranths often may be seen with three or five tentacles 

 not of a uniform size. 



This development in quartettes I have repeatedly observed in 

 regenerating hydranths of C. leptostyla, and the same thing 

 occurs in the egg development (Allman). In a recent paper 

 Paul Morgeustern ( '01, p. 567) shows that the first four tentacles in 

 Gordylophora, a near relative of Clara, appear in twos at the 

 same level. This is true also for Syncoryne (CoryneJ mirabilis 

 Ag. I have found that the regenerated distal tentacles in 



