VIII, D, 5 Light: Morphology of Eudendrium 335 



specimens were obtained, but no attempt was made to secure a 

 series for extensive study. The only female material collected 

 was part of a colony which formed a dense growth on a sponge, 

 most of the hydranths bearing verticils of gonophores. One 

 large male colony, bearing gonophores, was also growing on a 

 sponge. The other colonies, four in number, were growing on 

 the flat leaves of a seaweed, Thalassia hemprichi (Ehrenberg) 

 Ascherson ; ^ they bore only a few gonophores, all immature. All 

 measurements, descriptions, and figures are based on preserved 

 material. 



The hydrocaulus is monosiphonic, in the form of numerous 

 outgrowths of single or branched stems from a creeping filiform 

 hydrorhiza, which branches irregularly to form a network over 

 the surface of attachment. These outgrowths are more or less 

 recumbent, their height above the hydrorhiza being only 1 to 2 

 centimeters. They are numerous, crowded, and form a dense 

 gro-wth, having the appearance of a great number of single 

 pedicils arising from a common hydrorhiza. When branching 

 occurs, as it usually does, it is irregular as shown in fig. 1. The 

 buds arise both from the hydrorhiza and the hydrocaulus. The 

 only annulations to be found on Eudendrium griffim are from 

 2 to 6 more or less regular wrinkles found at the proximal end 

 of some of the pedicels. 



The hydranth of Eudendrium griffini is vase-shaped, unusually 

 long and slender, graceful in form, and delicate in appearance. 

 It expands gradually from a base often less than twice the diam- 

 eter of the pedicel to a region just proximal to the tentacle zone 

 which is from two and one-half to three times the diameter of the 

 pedicel. This increase in width is small when compared with the 

 length of the hydranth below the tentacle zone (1.2 to 2 mm.). 

 All measurements of hydranth lengths in this paper refer to the 

 length from the base of the hydranth to the tip of the tentacles. 

 These measurements are used because of the position of the 

 tentacles, which are distally directed and are so numerous and 

 closely packed as to hide the hypostome. This was possible as 

 the tentacles have not contracted irregularly in killing and fix- 

 ing as do those of so many hydroids. All hydranth measure- 

 ments, also, unless otherwise specified, are for the normal male 

 hydranth which I find to be normal for the species. The average 

 length of the hydranths (thus measured) is 2 to 3 mm., but they 

 vary remarkably in length and proportions. The length of the 



* Identified by Dr. W. R. Shaw, assistant professor of botany, University 

 of the Philippines. 



