THE CAMPANULAEID^ AND THE BONNEVIELLID^. 87 



OBELIA GRIFFINI Calkins. 



Plate 23, figs. 4-5. 



Obelia griffini Calkins, Some Hydroids from Puget Sound, 1899, p. 357. 

 Ohelia griffini Hartlaub, Hydroiden aus dem Stillen Ocean, 1901, p. 353. 

 Ohelia griffini Mayer, Medusae of the World, vol. 2, the Hydromedusse, 1910, p. 252. 

 Ohelia griffini Phaser, West Coast Hydroids, 1911, p. 39. 



TropTiosome} — Colony 21 mm. in height, consisting of a branched main stem with its rami- 

 fications. Main stem irregularly flexuose and with usually 3 or 4 strong aimulations above 

 each branch origin. Branches like the stem and alternate in position. The branches bear 

 alternate pedicels which are usually aimulated throughout their length and are almost always 

 shorter than the hydrothecse. Some of the pedicels which appear to be incipient branches are 

 much longer, sometimes more than twice as long as the hydrotheca. Hydrothecse smaller 

 than the preceding. The hydrothecse are deeply campanulate with almost parallel sides and 

 an even margin, sometimes almost triangular in lateral view. Diaphragm well defined, leav- 

 ing a rather deep basal chamber. 



Gonosome. — The gonangia are borne in the axils of the pedicels and are elongate-ovate 

 in shape and about three times as long as the hydrothecse. They have a well-defined shoulder 

 at the distal end, and a distuact collar surromiding the aperture. The developmg medusae are 

 not so numerous as m 0. gracilis and according to Calkins have about 24 tentacles at bnth. 



Distribution. — The type and only known locality is Puget Sornid. The exact locality 

 is not given by Calkins nor is it stated on the label of the specimen described. 



OBELU FRAGILIS Calkins. 



Plate 23, fig. 6. 



Ohelia fragilis Calkins, Some Hydroids from Puget Sound, 1899, p. 355. 



Ohelia fragilis Mayer, Medusae of the World, The Hydromedusae, vol. 2, 1910, p. 252. 



Obelia fragilis Fraser, West Coast Hydroids, 1911, p. 39. 



Trophosome.^ — Stems growing from a creeping rootstock parasitic on Aglaophenia stru- 

 thionides. Stem fascicled. As momited, the length is 16 mm. Manner of branching difficult 

 to ascertain in specimen which is much distorted, but it appears to be alternate, 3 to 5 rings 

 on the stem above each branch origm. Branches long and slender with a pedicel in the axil 

 of each. Pedicels, save the axillary ones, distant and alternate, very short, giving the hydro- 

 thecse the appearance of being sessile, and annulated and exceedingly slender and delicate. 

 Hydrothecse deeply campanulate, with very thin walls, margin not easily made out but appar- 

 ently even, or irregularly sinuous. The diaphragm is well defined and the basal chamber con- 

 tinuous with the stem cavity. 



Gonosome. — Not known. 



Distribution. — The type-locality is Port Townsend Harbor, Puget Sound. No other locality 

 has been recorded. 



Genus OBELARIA Hartlaub. 



Obelaria Hartlaub, Die Hydromedusen Helgolands, 1897, p. 489. 



The following is a translation of the original definition of this genus : 



Stem branched in a treelike manner, compound, springing from a felted spongy rootstock. Hydrothecse cam- 

 panulate, without operculum. Hydranth vdth a protruding contl-actile proboscis. Gonangia borne on the stem and 

 twigs, containing sporosacs. The development of the egg takes place outside of the gonangium. 



This genus differs from Obelia in the fact that it does not produce medusae, and from 

 Campanularia in the fact that the planula is developed outside, instead of within, the gonangium. 



1 Description of a colony mounted on a slide and kindly loaned the writer by Dr. Gary N. Calkins, the original 

 describer of this species. 



^Description of type specimen, kindly loaned the author by Doctor Calkins. 



