30 University of California Publications. [zoology. 



A single colony covering the shell of Nassa menblica. Some 

 of the medusae were about ready for liberation (March 25, 1895) . 

 Fam. Clavid.e. 



Trophosome. Hydranths elavate or fusiform, with scattered filiform ten- 

 tacles. 



Gonosome. Gonophores fixed sporosacs. 



Clava, Gmelin. 



"Trophosome. Hydroeaulus rudimental and consisting of very short 

 tubular processes from the free surface of a hydrorhiza which is composed 

 of creeping tubes, either distinct or adnate to one another by their sides, and 

 invested, as well as the rudimental hydroeaulus, by an obvious perisarc. 

 Hydranths claviform. 



" Gonosome. Sporosacs springing from the body of the hydranths at the 

 proximal side of the tentacles." Allman, '71. 



Clava leptostyla Ag. 



PI. I. Pigs. 5, 8, 9, 10, 11, 12. 

 Clava leptostyla, Ag., Contr. N. H. U. S., 1862, IV, p. 218. 



Distribution. San Francisco Bay, Cal. Massachusetts Bay 

 (Agassiz). Great Britain (? ) (Hincks). Between tides. 



Found the year round, with sporosacs, in Oakland Harbor, 

 (brackish water) . The sexes of this species are ordinarily sep- 

 arate, but occasionally a colony will be found with individuals of 

 both sexes, one predominating greatly, however; instances of 

 hermaphroditic gonophores have been met with also. 



Regeneration. This species regenerates readily. Pieces cut 

 from a hydranth may produce hydranths at each end. (Figs. 8,9). 

 The basal portion of the hydranth, if left attached to the stolon, 

 will produce tentacles and a mouth. The development of the 

 tentacles on one such piece was followed. During the night 

 after the animal was sectioned four tentacles appeared at the 

 same level (Fig. 10), and, to judge by their equal length, sim- 

 ultaneously. The next four appeared simultaneously just prox- 

 imal to and alternating with these (Fig. 11). The third four 

 appeared simultaneously, proximal to these directly in line with 

 those of the first quartette (Fig. 12). The scattering of the 

 tentacles evidently takes place later. 



According to Allman's observations on C. squamata, the 

 tentacles appear on the flxed planula in the same way; so that 



