22 University of California Publications in Zoology. [Vol.6 



I have not been able to connect this immature medusa defi- 

 nitely with any adult of these waters. It is almost identical with 

 Fewkes' (1882) description and figures (ID and 20) of the 

 young of Phialium duodecimali Haeckel. The chief difference 

 consists in the presence of two gonads in the San Diego form. 

 Specimens of adult Phialium have not yet been found near San 

 Diego. The interradial position of the statocysts of the young' 

 prevents an easy transition to Euchiloia, or the medusa sug- 

 gested as a young Phialopsis brownei. 



The hydroid is known from Oceano and San Diego, both on 

 the coast of Southern California. It is found attached to the 

 shells of mollusks, mainly clams ( Tivela stultorum at Oceano, 

 Donax Ioa vigata at San Diego), that inhabit fiat, sandy, ocean 

 beaches. 



Gen. Phialidium Leuckart, 1856. 



Eucopidae with numerous tentacles and at least as many stat- 

 ocysts lying between them; gastric peduncle and marginal cirri 

 wanting. 



Phialidium lomae,- n. sp. 



Pig. s. 



Umbrella thin, about four times as broad as high. Manubrium 



short, with slightly frilled lips. Tentacles 28-34, rarely more. 



Fig. S.-^Fhialidium lomt> 



X 6. 



One, occasionally two. statocysts with single statoliths between 

 adjoining tentacles. Gonads narrow in adult, confined to distal 

 half of radial canals. Gonads, canals, tentacles and manubrium 

 faint yellow, umbrella very transparent. 



Named for Point Loma, San Diego. 



