160 EXPEDITION OF THE "ALBATROSS," 1899-1900. 



DIPHYOPSIS APPENDICULATA. 



ERS^A APPENDICULATA. 



Diphyopsis appendiculata Agassiz and Mater. 



Diphyes appendiculata Esc hscikutz, F.. 18-29; Syst. der Acalephen, p. 138, Taf. XTI., Fig. 7. 

 Diphyes appendiculata Huxley, T. II., 1859; Oceanic Hjdrozoa, p. 34, PI. I., Figs. 2-2<:. 



Plate 9, figs. 38, 39. 



This species was first obtained by the "Albatross" in N. lat. 17° 32', 

 W. long. 135° 40', and it continued to be abundant throughout the tropical 

 regions of the Pacific. In tlie Pacific species the entoderm of the poljpites 

 and nematocj-st batteries is milky, or slightly yellow or jiink in color, wdiile 

 in the Atlantic form the poljpites are of a more or less intense green and 

 the nematocyst batteries of the tentacles are yellow or orange (see Bull. 

 Mus. Comp. Zool., Vol. XXXVII., No. 2, PI. 34, Fig. 114). A still more 

 important difference between the two species lies in the fact that in the 

 Pacific form the monogastric sexual generation belongs to the genus Ersoea, 

 and lacks a manubrium within its swimming-bell; while in the Atlantic form 

 it belongs to tlie genus Eudoxia, for it possesses a manubrium within its bell. 

 The Pacific form, therefore, is a Diphyopsis, while the Atlantic form belongs 

 to the genus Diphyes. 



The animal is 18-20 mm. in lenglh, and the anterior swimining-bell 

 is somewhat larger than the posterior. Tlie anterior bell is angular and 

 pyramidal and its cavity is voluminous. There are two ascending, curved 

 radial canals and a simple circular ves.sel. The phyllocyst is long and 

 narrow and contains an "oil globule" near its distal extremity. There is 

 a moderately deep conical hydroecium upon the ventral face of the anterior 

 nectophore, and the siphosome arises from its inner apex. The first appen- 

 dage of the siphosome is the large posterior swimming-boll (jJS, Fig. 39). 

 This is somewhat smaller than the anterior bell, and a deep groove covered 

 by a projecting tooth runs down the side upon which the siphosome is situ- 

 ated. Indeed the siphosome lies within this groove and is protected by 

 the covering tooth. The second appendage of the siphosome is the small 

 auxiliary swimming-bell (a s, Fig. 39). Immediately below this comes a 

 cluster of immature feeding polypites, the older ones being successively 



