44 University of California Publications. [zoology. 



shape." Fig. 15, PI. XXIII of his work, however, shows a 

 raised welt at the edge of the bell mouth, divided by radial 

 wrinkles into a number of rudimentary processes. Fig. 22 of 

 the present paper represents a male gonophore drawn at San 

 Pedro from life, on which there are eight unmistakable flattened 

 tentacular processes. It does not represent the condition 

 in all male gonophores, however, for these tentacular pro- 

 cesses vary in size almost to the vanishing point. The shape 

 of the bell is not constant, either, though varying far less than 

 that of the female gonophores. All of these variations in size 

 and shape are due either to different degrees of contraction — 

 which applies especially to the tentacular processes; or to the 

 nature of the contents — which applies especially to the shape of 

 the gonophores. The female gonophores are less symmetrical 

 than the male only when they become distorted by the growth of 

 the contained embryos, which often number four or even more. 



I have seen actinulas liberated at Oakland in September and 

 at San Pedro in July, August and December. Specimens dated 

 May 10, 1898, in the University of California collection, have 

 heavily loaded male gonophores. 



In midwinter, headless stems only are found ordinarily in Oak- 

 land Harbor. At the same time of year the species is growing 

 luxuriantly at San Pedro where it is found the year round. The 

 difference is perhaps to be explained by a difference of habit. 

 The headless stems in Oakland Harbor are attached to fixed sup- 

 ports, such as the piles of wharves and bridges, sometimes as 

 many as three feet above mean low water mark. Consequently 

 they are exposed to the air at least once a day, at ebb tide. On 

 the other hand, the San Pedro colonies which grow so luxuriantly 

 the year round are attached as a rule to floating timbers, unused 

 barges and other floating supports; consequently they are never 

 uncovered at ebb tide. It is possible that the severity of the 

 diurnal change to which the Oakland colonies are subjected during 

 the winter is the cause of the loss of the hydranths. Whether 

 well formed colonies continue below mean low water through the 

 winter I cannot say positively, but so far as 1 have been able to 

 see from the surface at low tide, they do not. If they do not, 

 then it is probable either that the temperature of water is too low 



