14 University of California Publications. [| ZOOLOGY 
(Agassiz). Iceland, British coasts (Hincks). Norway (Sars). 
Helgoland (Hartlaub). White Sea (Mereschkowsky ). 
No gonosome in the San Diego specimens, June 26, 1903. 
Gen. Obelia, P. et L., 1809. 
17. Obelia corona, n. sp. 
Trophosome. Colonies very low; stems simple, short, slightly flex- 
uous, from a creeping stolon, with 3-6 annulae distal to each pedicel. 
Hydranths long, narrow, tapering, margin with 8-10 teeth, each with two 
sharp eusps, pedicel short, completely annulated, with 2-4 annulae. 
Hydranth with about 24 tentacles. 
Gonosome. Gonangia about 3 times as long as broad, with wide 
aperture; pedicel slender, with 2-4 annulae. Numerous medusae, largest 
with 24 tentacles. 
Dimensions. Hydrotheea: .44x.20; .43x.18 mm. 
yonangium: .76x.20 mm. (including pedicel). 
ASA 
Fig. 5.—Obelia corona. Fig. 6.—O. corona. Gonangia. 
Hydrotheeae. 
Distribution. San Diego Bay, on piles under wharves at low 
tide, July 15, 1904. Creeping over sponges. 
Hydranths and gonangia are frequently borne on pedicels 
springing directly from the stolon. Stems and stolons transform 
with readiness into each other in the colonies at hand, owing 
doubtless to the many opportunities offered by life on a growing 
sponge for variations in the contact stimulus. 
