ANTHOMEDfS.E I'ENNAHI \. 27 



water, and are often retained until they wither upon the stems after having cast out their 

 genital products. 



I have found only the pale form of Pennarin on the Florida Reefs, and its medusae appear 

 to cast out their genital products before being set free, as is described by Hargitt for the deep- 

 water forms of Woods Hole, Massachusetts. In Florida, Pomona grows in tuft-like clusters 

 upon gorgonians. This tropical form is called Pennana gtbbosa by L. Agassiz, but those seen 

 by me can not be separated from the Pennaria of the coast of New England. 



Hargitt, 1899, carried out a series of grafting experiments upon Pennaria and other 

 hydroids. He finds that pieces of hydroids of the same species may readily be grafted one 

 upon the other, both in oral or aboral relations, there being little or no evidence of polarity 

 in the regenerative process. Pieces of opposite sex but of the same species will readily unite 

 in any manner, but pieces belonging to hydroids of different genera would not unite. Elaborate 

 studies of this character were also carried out by Gast and Godewski, 1903, on P. Jisticha. 



In 1900 and 1901, Hargitt studied the variations of the medusx and hydroids of Pen- 

 naria. The medusa sometimes displays ectodermal blister-like protrusions on its exumbrella, 

 and is variable in other respects. 



According to H. Miiller, 1907 fZeit. fur wissen. Zool., Bd. 89), the eggs of Pennaria 

 develop at the expense of the weaker egg-cells of the ovary, which they engulf as food to form 

 the yolk-granules. 



Thacher, 1903, shows that in Pennaria, Campaniilana, and EiiJenJnurn, the hydranths, 

 when they degenerate, are absorbed not by liquefaction of their protoplasm, or by the with- 

 drawal of the polyps as a whole; but absorption takes place by the degenerating cells of 

 both ectoderm and entoderm being turned into the digestive tract of the hydroid. 



Goldfarb, 1906, finds that light is absolutely essential for the normal growth, develop- 

 ment, and regeneration of Pennaria. He finds, however, that this is true in a sense also for 

 Eudendrium, but not to the same degree, for Eudendrnim ramositm colonies, kept in the 

 dark until all the influence of their previous illumination has been lost, will not then 

 regenerate new hydranths unless they be again exposed to light; but the surprisingly short 

 exposure to light of only 5 seconds will suffice to restart the regenerative process. 



Pennaria rosea von Lendenfeld. 



Pennaria rosea, VON LENDENFELD, 1884, Proc. Linnean Soc. New South Wales, ser. I, vol. 9, p. 51)4, plate 24, figs. 40, 42. 

 BALE, 1888, Ibitl., ser. 2, vol. 3, p. 747 7*. australii, BALE, 1884, in Cat. Australian Hydroid Zoophytes, p. 45. 



Main axial stems 80 mm. long, with about 20 alternately arranged, pinnate side branches. 

 4 to 6 hydranths on each branch. Hydrorhiza and main stems intensely black and opaque; 

 outer half of each stem light-yellow, proximal half intense black. Hvdranths rose-colored, 

 with 9 to 14 oral, and 7 to 12 filiform, basal tentacles. Medusas are produced on the proximal 

 hydranths. The medusa bell is slender, oval, 2 mm. high, I mm. wide. 4 large rudimentary 

 tentacle-bulbs with a minute external ocellus upon each. Manubrium with sperm or ova fills 

 the entire cavity of subumbrella. Ova discharged after medusa is set free. Color, intense rose. 



Coast of New South Wales, Australia. Mature in May. 



This species is distinguished from the European and American Pennaria by its tentacu- 

 lar ocelli. 



Pennaria adamsia von Lendenfeld. 



Pennaria aaamsia, VON LENDENFF.LD, 1884, Proc. Linnean Soc. New South Wales, vnl. 9, p. 595, plate 25, figs. 45-48; plate 26, 

 fig- 49- 



MeJusir. The male medusae are 1.5 mm. long and only 0.7 mm. wide; while the female 

 medusas are 1.5 mm. long and as broad as they are high. The male medusas have 4 radially 

 situated marginal tentacles, about as long as the width of the bell. These tentacles have 

 well-developed basal bulbs with minute ocelli, and the tentacles move about freely. The 

 spermatozoa fill the space between the manubrium and the sides of the subumbrella, and are 

 discharged within an hour after the medusa has been set free. The female medusas are 

 broad, and the tentacles are mere rudiments without ocelli. The bell-cavity is filled with 

 ova, which are soon discharged. 



