38 SEA-SHORE LIFE 
inches high, and resembles a little dark-colored tree with branches 
arranged alternately on either side of the main stem. Each branch 
gives rise to a series of side branches on its upper side and they 
each and all terminate in white or pink flower-like heads. These 
polyp-heads bear the mouths, and each is surrounded by two rows 
of tentacles which wave through the water intent upon the capture 
of the small marine animals upon which the Pennaria feeds. Jelly- 
fishes grow out from the sides of the polyp-heads, and within these 
the eggs develop At times the eggs are cast out before the jelly- 
fishes are set free, but often the jellyfish escapes from the 
hydroid and swims about, car- 
rying its eggs with it. The 
eggs then develop into little 
pear-shaped larvee which swim 
rapidly through the water but 
soon settle down and change 
into tree-like hydroids which 
in turn develop another genera- 
tion of jellyfishes. 
In spring and early sum- 
mer large, pale colored, stocks 
of Pennaria are found upon 
rockweed, piles, etc.; but about 
the middle of August small, 
highly colored stocks, with pink 
heads, are found in great abund- 
ance upon eel grass. This was 
observed by Professor Hargitt 
in “The American Naturalist,” 
Vol. XXXIV, p. 390. 
The Sea Plume, ( Obelia com- 
missuralis, Fig. 14), is common 

upon the wooden posts of wharves 
Fig. 14; SEA-PLUME (Obelia), Growing or attached to stones or sea-weed. 
Upon Seaweed ( Fucus). From Life. : 
The main stems are fully six 
inches long, and they give rise to spirally arranged branches which 
run nearly at right angles to the stem. The creature thus resem- 
