CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 15 



GENERIC CHARACTERS. 



Body oval or egg-shaped, sagittal diameter almost as great as the 

 tentacular axis. The animal resembles Pleurobrachia except that the 

 tentacles usually bear two or more kinds of side branches instead of 

 simple filaments. Also in Hormiphora the tentacle bases arise from the 

 bottom of deep clefts close to the sides of the paragastric vessels while 

 in Pleurobrachia the clefts are not so deep and the tentacle bases are 

 situated at points about half-way between the sides of the paragastric 

 vessels and the outer surface of the body. 



The type species is Hormiphora plumosa of the Mediterranean. 



This genus is so closely allied to Pleurobrachia that I consider its 

 separation to have been unfortunate and future discoveries of forms will, 

 I beHeve, reveal intergrades and oblige us to unite the two genera under 

 the older name Pleurobrachia. 



Moser, 1903, gives a diagnosis of all of the species of Hormiphora 

 known at that time, and in 1909 she gives a Hst of species with their 

 geographical ranges. 



Hormiphora plumosa L. Agassiz. (Figs. 5 to 80, plate 2.) 



Cydippe hormiphora, Gegenbaur, 1856, Archiv ftir Naturgesch., p. 200, Taf. 8 

 fig. 10. 



Cydippe plumosa. Sars, M., 1856, Middelhavets Litt. Fauna, p. 71. 



Hormtpliora plumosa, Agassiz, L., i860, Cent. Nat. Hist. U. S., vol. 3, p. 196.— 

 Chun, 1880, Fauna and Flora des Golfes von Neapel, Monographic i, pp. 64, 

 281, Taf. I, Fign. 5, 6; Taf. 2, Fign. 2, 3; Taf. 3, Fign. 8, 9.— Mayer, 1900, 

 Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 82.— Moser, 1903, 

 Ctenophoren der 5tfeoga-Expedition, p. 10. — Samassa, 1892, Archiv Mikro- 

 skop. Anatomic, Bd. 40, pp. 173, 223 (histology).— Ghigi, 1909, Ctenofori, 

 Fircnzi, vol. 2, p. 14. 



Cydippe densa, Spagnolini, 1870, Cat. Ber. Golfo. d. Napoli, Bull. d. Nat. e Med. 



Napoli, p. 61. 



This Mediterranean species is occasionally found near the surface 

 upon calm days in svunmer at the Tortugas, Florida, and thus it is ap- 

 parently distributed from the Mediterranean across the tropical Atlantic. 



The body is about 15 to 20 mm. long, oval, with bluntly rounded 

 aboral pole and more or less narrowed oral pole, giving an egg-shaped 

 outline. The shape of the body changes, however, with the states of 

 contraction of the animal and may vary considerably in ratio of width 

 to length. There is practically no lateral compression, the cross-section 

 of the body being very nearly circular. The apical sense-organ is simple 

 and not appreciably sunken beneath the surface, and the apical pole- 

 plate bears no protuberances. There are 2 excretory pores. The 8 

 meridional rows of ciliated combs are all equal each to each in length. 

 They begin at a considerable distance below the apical sense-organ and 

 extend to the lower third of the body. The 8 meridional vessels do not 

 extend far below the lower ends of the rows of combs. There are 

 about 25 to 40 combs in each row. Of the chymiferous vessels, the 

 2 perradial are extremely short, the 4 interradial qiiite long, and the 8 

 adradial about as long as the interradial. The funnel-tube is well devel- 

 oped and tapers so as to be narrowest near the apical sense-organ. The 

 stomodseum and 2 lateral paragastric tubes are simple and narrow. The 



