60 AMEKICAN HYDBOIDS. 



with a membrane that ruptures for the passage of the medusae. Gonangial contents developing 

 medusse which are described as follows by Mayer, 1910:" When set free the beU is oval, thin-walled, 

 with 2 well-developed and 2 small, immature tentacles. 4 radial-canals. 2 gonads, 4 Hthocysts. 

 Cirri flank the basal-bulbs of the large tentacles." 



Type-locality. — Pacific Beach, near San Diego, Cahfornia. In the surf, also found at times 

 in great quantities at Long Beach and Torrey Pines Beach, near La JoUa, Cahfornia. 



This is perhaps the only known instance of hydroids being present on hving bivalves. 



CLYTIA EDWARDSI (Nutting). 



Plate 13, figs. 3, 4. ■ 



Campanularia johnstoni Calkins, Some Hydroids from Puget Sound, 1899, p. 349. 



Cdmpanularia gracilis^ Calkins, Some Hydroids from Puget Sound, 1899, p. 350. 



Campanularia edwardsi Nutting, Hydroids of the Woods Hole Region, 1901, p. 346. 



Campanularia edioardsi Torrey, Hydroids of the San Diego Region, 1904, p. 11. 



Clytia edwardsi Fraser, West Coast Hydroids, 1911, p. 34. 



Clyiia edwardsi Fraser, Notes on Some New England Hydroids, 1912, p. 44. 



Clytia edwardsi Stechow, Hydroidpolypen der japanischen Ostkiiste, vol. 2, 1913, p. 69. 



Trofhosome? — Colony profusely but irregularly branched and attaining a height of 2.5 cm. 

 Stem, branches, and pedicels all exceedingly attenuated and without any regular disposition, 

 although the pedicels show a tendency to occur in pairs springing from opposite sides of the 

 branch. The branches are smooth, except for a group of four or five regular annulations at their 

 bases. Pedicels sometimes as much as 7 mm. in length and perfectly smooth, except for a 

 group cff three to six annulations just below the hydro theca and a more numerous group at the 

 base. Hydrothecse elongate, campanulate, approaching a tubular form, being sometimes 

 three times as long as wide. Margin armed with 12 to 14 sharply pointed teeth. There is a 

 well marked diaphragm and a rather deep basal chamber. 



Gonosome? — ^Gonangia borne on the stem and branches usually in the axils of the pedicels, 

 elongate obconoid in shape in some cases, almost tubular in others, and about 1.5 mm. in length 

 and three to five times as long as wide. The walls are rather rudely and irregularly annulated 

 throughout. On the blastostyle are seen several developing medusse which seem to be semi- 

 globular in shape with four ( ?) tentacles and a well-developed proboscis. 



Distribution. — Type-locahty, Woods Hole, Massachusetts (Nutting) ; reported by Torrey 

 from the mouth of San Diego Bay; and by Fraser from Vancouver Island; Japan (Stechow). 

 If I am right in considering Campanularia gracilis of Calkins to be a sjmonym for this species 

 its range should also include the Puget Sound region. 



Doctor Fraser's specimens were directly compared with the type from Woods Hole, Massa- 

 chusetts, and were indistinguishable so far as the trophosome was concerned. Since writing 

 the above Doctor Fraser has found the gonosome on specimens from the Woods Hole region 

 and regards them as identical with those above described. 



CLYTIA ATTENUATA (Calkins). 



Plate 13, fig. 5. 



Campanularia attenuata Calkins, Some Hydroids from Puget Sound, 1899, p. 350. 

 Clytia attenuata Fraser, West Coast Hydroids, 1911, p. 34. 



Trophosome.* — Colony growing in tufts of stems springing from a creeping rootstock. These 

 stems attain a height of about 9 mm. and are usually smooth, although there is an occasional 

 annulation above a pedicel origin. The branching is very straggHng and irregular, each branch 

 from the main stem usually being a single long slender pedicel. Sometimes two branches occur. 

 The pedicels are long and slender and are bent abi-uptly upward near their bases so as to he 



' Name preoccupied. 



^ Described from a type-specimen collected at Woods Hole by the author. 



3 Described from a specimen from Departure Bay, Vancouver Island, collected by Dr. Charles McLean Fraser. 



* Description of one of Calkins's specimens mounted on a slide and kindly loaned me by Doctor Calkins. 



