CALKINS: SOME HYDROIDS FROM PUGET SOUND. 353 
forms only a part of the diaphragm (PI. 6, fig. 12 f). T he margin 
is perfectly smooth. The hydranth has many tentacles (28-30). 
The hydrorhiza is much branched. 
Gonosome. Gonotliecae borne on hydrorhiza, elongate, slightly 
oval with truncate end. The blastostyle produces eggs directly 
(PI. 2, fig. 12). The wall of the gonotheca is heavily ribbed. 
Diaphragm. The thickening at the base forms a part of the 
diaphragm, but the hydranth rests mainly upon a thin ledge or shelf 
of chitin which extends inward from the upper part of the thickened 
portion. This shelf gives a characteristic appearance to the coeno- 
sarc which, in order to pass through the narrow aperture, is consid¬ 
erably constricted at this point, swelling out below to partly fill the 
basal chamber (PI. 6, fig. 12 f). 
Dimensions. Length of stem, 6-8 mm.; length of hydrotheca, 
.6 mm.; width of margin, .3 mm.; number of tentacles, 28—30 ; 
length of gonotheca, 1.5-1.8 mm.; greatest width, .65 mm. 
Habitat. On red algae off Point Wilson, Port Townsend, and 
Bremerton. Common. Previously reported from England (various 
authors); Labrador (Hincks); Spitzbergen (Marktanner-Turne- 
retscher); Alaska (Clarke); Greenland (Levinsen). 
13. Campanularia exigua Sars. PI. 4, figs. 19, 19 a, 19 n. 
Laomedia exigua Sars. 
Stems very delicate, slightly fiexuous, giving off simple pedicels 
at each bend, ringed at base and above each branch. Hydrotheca 
small, regularly funnel-shaped, with smooth and even rim. Gono- 
thecae (Hincks) axillary, elongate, smooth, somewhat fusiform. 
The diaphragm is simple, extremely fine and difficult to see. 
The basal chamber is contained in the hydrotheca. 
Without the gonophore I cannot place this species more definitely. 
It is a ragged looking form, the rough and irregular coenosarc 
filling the stem. The margin of tlje bell is often sinuous and wavy. 
D imensions. Height of colony, 6-7 mm.; length of hydrotheca, 
.4 mm.; width at margin, .3 mm. 
Habitat. Port Townsend, on stones, etc. 
14. Obelia gracilis sp. nov. PI. 3, figs. 13, 13a, 13b, 13c. 
PI. 6, fig. 13 d. 
Trop)hosome. Hydrocaulus erect, simple, or slightly branched, 
growing on a creeping and slightly branched hydrorhiza. Primary 
stem with from four to six annulations at the base and with from 
one to three above each branch or hydrotheca stem. The branches 
