.\\TIIOMK1HS.K - siltiKilTA, NlolilA. 187 



above the mouth and the stomach is urn-shaped and cruciform in cross-section. The 

 4 gonads are on the interradial sides of the basal part of the stomach and consist of 2 bow- 

 like longitudinal ridges in each interradius. These ridges are crossed by furrows as in Ti.nin.i-. 



The entodermal parts are brown or almost black, but this color may be due in some- 

 measure, il not whollv, to the method of prcsi-rvation. 



A single preserved specimen is described by Maas. It was captured in an open vertical 

 net between 450 fathoms and the surface, in the Malav Archipelago, near the Celebes, in i ' 28' 

 N. lat., 124 28.2' E. long. 



Sibogita simulans Bigelow. 



SiboRita simulans, Bn.now, H. B., 1909, Mem. Mus. Cmnp. Znnl. at Harv.ir.1 CcdliTi-. rol. ;-. p. ;i;. pl.it.- ;, 41. an, I 4;. 



This medusa may prove to be identical with S. ^i-nnii-him Maas. 



Bell 30 mm. high, 22 mm. wide, laterally flattened, apex dome-like and rounded, gelati- 

 nous substance thick. Manubrium barrel-shaped, one-third as long as depth of bcll-caviiy. 

 Its base is 4-sided. 4 interradial gonads each consisting of a double, transverse row of folds 

 on the sides of the stomach. Lips well developed. There are 4 main radial-canals. In young 

 medusae the ring-canal gives rise to 8 adradial, blindly ending centripetal vessels. In later 

 life these adradial vessels connect with the stomach and 4 new interradial vessels make their 

 appearance and also connect with the stomach. Thus the medusa has 4 radial-canals and 

 12 vessels which arise from the marginal ring-canal and secondarily connect with the cruci- 

 form arms of the stomach. When mature there are 50 tentacles, one opposite each canal 

 and the others somewhat irregularly arranged. The tentacles are long, hollow, and flexible 

 and terminate in a knob of nematocysts. They have no basal bulbs and no ocelli. 



The gonads are reddish-brown; bell faint blue. 



2 specimens were found on the surface in the tropical Pacific between the Galapagos 

 Islands and Panama; another from Behring Sea, 121 fathoms. 



Genus NIOBIA Mayer, 1900. 

 Niohia, MAYF.R, 1900, Bull. Mus. Comp. Zool. at Harvard Gillci;<-, vnl . 37, p. ^(,. 



GENERIC CHARACTERS. 



Dendrostaurinae with 4 main radial-canals, 2 of which bifurcate, so that Ci canals reach 

 the circular vessel at the bell-margin. The gonads are developed on the 4 interradial sides of 

 the stomach. The mature genital products are found in the ectoderm. There are 4 simple 

 lips, but no oral tentacles. The marginal tentacles develop into medusa- by a peculiar process 

 ot budding combined with fortuitous growth and are set free into the water as independent 

 animals similar to the parent medusa. 



The only known species is Niobia dendrotentacula of the Tortugas, Florida. 



Niobia dendrotentacula Mayer. 



Plate 19, figs. 1-5. 

 Niobia ilrndroltntarula, MAYER, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 36, figs. 141-144, plates 42, 4-,. 



Adult medusa (plate 19, fig. 5). The bell is slightly flatter than a hemisphere and about 

 4 mm. in diameter. The outer surface is smooth and there is no apical projection. The 

 gelatinous substance of the bell is quite thin and uniform, but not very flexible. 



4 radial-canals arise from the 4 corners of the stomach; but 2 of these canals, which are 

 diametrically opposite each other, bifurcate so that 6 radial-canals reach the circular vessel 

 at the margin, 60 apart. 



There are 12 marginal tentacles, one at the foot ot each radial-canal and one inter- 

 mediate between each successive pair of radial-canals. These 12 tentacles are arranged in 

 a bilaterally symmetrical manner in accordance with age. The rtldest and the youngest 

 tentacles are situated at the ends of the 2 simple radial-canals and the remaining 10 tentacles 

 are arranged in bilateral symmetry in accordance with their various ages, the axis being in 

 the diameter of the 2 simple radial-canals and the oldest and youngest tentacles. Kach halt 

 of the margin is thus a reflection of the other, and the order in age of each tentacle is shown 

 in plate 19, fig. 4. where (l) represents the oldest, (2) the next oldest, and (/) the youngest 



