696 MEDUSA OF THE WORLD. 



The 8 mouth-arms when contracted are harJI)- longer than the bell-diameter. The 

 lower arms are free and taper to their pointed lower ends. They are about 6 times as long as 

 the upper arms. At the upper end of each of these lower arms there are 2 abaxial wings so 

 that the arm is here j-winged in cross-section and the frilled mouths are developed onl\ along 

 the thin edges of the 3 membranous wings. The main shaft of the lower arm is, however, 

 triangular in cross-section and the mouths are developed upon the sides as well as upon the 

 angular edges of the arm. Each lower arm terminates at its pointed lower end in a long, 

 tapering filament which is about two-thirds as long as the lower arm itself. Numerous, short, 

 slender filaments arise from between the mouths, especially along the lines of the angular 

 edges of the lower arm. There are no club-shaped appendages. 



Stomach cruciform, the arms of the cross wide and not quite as long as the center, where- 

 in the arms come together. Thus the stomach is relatively wider than in other species of 

 Lonfera. The canal-svstem of the bell consists of 8 canals in the radii of the sense-organs, 

 which are put into communication one with another by a network of anastomosing vessels 

 which arise not only from the 8 radial-canals but from the edges of the stomach. There 

 is no clearly developed ring-canal and it is difficult to determine the number of canals which 

 arise from the stomach between each successi\e pair of rhopalar canals. There is a very wide 

 zone of circular muscle-fibers in the subumbrella. This muscle is onlv somewhat thinned but 

 not actuall)' interrupted in the 8 principal radii. The 4 gonads are horseshoe-shaped and com- 

 ple.\ly folded. This medusa is found at the Hawaiian Islands and in the Malay Archipelago. 



In a small specimen found by the U. S. Fisheries Bureau steamer Albatross at station 

 D 5226, in the Philippine Islands on Ma\- 4, 1908, the bell is 50 mm. wide and mouth-arms 

 56 mm. long, the slender, tapering filaments at the ends of the arms being 18 mm. and the 

 mouth-bearing parts of the arms 38 min. long. 



Genus LEPTOBRACHIA Brandt, 1838. 



Leptohrachia, Brandt, 1838, Bull. Acad. Sci. St. Pctcrsbourg, tome i, p. 191. — .Agassiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, 



p. 154. — Maas, 1903, Scyphomc-Jusen der Siboga Exped., Monog. 11, p. 81. 

 Lepiohrachia + Leonura, Haeckil, 1880, Syst. der Medusen, pp. 630, 631. 

 Ltonura, Haf.ckf.l, lS8l, Deep-Sea Medusa- Challenger Expedition, Zool., vol. 4, p. 133. 

 Leptobrachia + Leonura, Vanhoffen, 1888, Bibliotheca Zoologica, Bd. i. Heft. 3, p. 45. 



GENERIC CHARACTERS. 



Rhtzostomata lorijera in which the long, linear mou:h-arms bear no frilled mouths near 

 the middle ot their lengths; but near rheir poin"s of origin from the arm-disk there is a ventral 

 row ol mouths, and below the naked mid-region there are 3 lines of mouths, I ventral and 2 

 dorsal. The mouth-arms terminate below in a naked pointed end, free of mouths. 



Among characters of minor importance, the slit-like subgenital ostia are wider than the 

 columns between them. 16 radial-canals extend to the bell-margin and a well-developed 

 ring-canal gives off a network of vessels on both ifs inner and outer sides; these networks 

 fuse with the radial-canals. A unitar\, circular muscle is in the marginal zone of ihe sub- 

 umbrella. 



Leptobrachia leptopus Brandt. 



Rhitosloma leptopus, Chamisso et Eysenhardt, 1821, Nova Acta Phys. Med. Nature Curios., tome 10, p. 356, taf. 27, fign. i, 



A and D. 

 Leptobrachia leptopus, Brandt, 1838, Bulletin Acad. Sci. St. Pctersbourg, tome i, p. 191. 

 Leonura terminalis, Haeckel, E., 1880, Syst. der Medusen, p. 646; 1881, Deep-sea Medusar Challenger Expedition, Zool., vol. 4, 



p. 133, plate 32, figs. 1-8. 

 Leonura leptura, Haeckel, 1880, he. eit., p. 631. 



The following description is derived from Haeckel's account of his "Leonura termi- 

 nalis" which is onl}' a modern name for Brandt's Leptobrachia leptopus =Rhizostoma leptopus 

 Chamisso and Eysenhardt. 



Bell flatter than a hemisphere, So mm. wide. Exumbrella covered with regularly arranged, 

 polygonal elevations bordered by furrows. 8 rhopalia. 80 marginal lappets. All of the 

 lappets are sharply pointed and are largest at the middle of each octant, the smallest being 

 adjacent to the rhopalia, the lappets increasing successively in size and being largest midway 



