ISO 



.MKDFS.E OF THE WOULD. 



radial, swollen gonads, with transverse furrows and a longitudinal median groove. I believe 

 this to be identical with Giinther's medusa. Having 5 primary radial-canals it may be 

 abnormal. 



Genus SIBOGITA Maas, 1905; sens, emend Bigelow, 1909. 



Sibo^ii'i, MAAS, 1905, Craspedoten Medusrn Jrr Xibo^a Expedition, Monnp. 10, p. 16. -Bn^Lnw, H. B., 1909, Mem. Mus. 

 Cnmp. Znol. at Harvard Collegi-, vol. 37, p. 213. 



The type species is Sibogita geometrica Maas, from the Malay Archipelago. 



GENERIC CHARACTERS. 



Bythotiaridi with 4 main radial-canals. The marginal ring-canal gives off a number 

 of centripetal canals which in young specimens end blindly, but in later stages they connect 

 with the cruciform base of the stomach. The gonads consist of a pair of ridges with cross 

 furrows on each of the 4 interradial sides of the stomach. The tentacles are hollow and are 

 situated at the ends of the larger canals. 



It is probable that this genus has been phylogenetically derived from some Turris-like 

 medusa. 



Sibogita geometrica Maas. 

 Sibogita geometric,!, MAAS, 1905, Craspcdoten Medusen der Siboga Eipcd., Monog. 10, p. 17, taf. 3, fign. 16-18. 



Bell is 40 mm. high, 20 mm. wide; with bulging, laterally flattened, barrel-shaped sides 

 and flatly rounded top. Gelatinous substance uniform and quite thick. There are 16 slender, 

 hollow tentacles, with swollen, club-like outer ends. These tentacles arise from the ring-canal 

 at the bases of the 16 larger canals and they project from the sides of the bell at a short distance 

 above the margin, as in Narcomedusae. The entodermal cores of the tentacles extend through 



the gelatinous substance of the bell to the ring- 

 canal, and the margin between the tentacles is 

 thrown into 16 gelatinous"lappets." Thetentacles 

 are about three-fourths as long as the bell-height, 

 but are highly contractile. Their bases are only 

 slightly swollen and there are no ocelli. 



There is a marginal ring-canal which gives 

 rise to centripetal branches. According to Maas, 

 4 wide, main radial-canals arise from the 4 cor- 

 ners of the stomach and proceed straight to the 

 ring-canal. 2 or 3 alternately arranged branches 

 fuse with the sides of each of these main radial- 

 canals. The largest (oldest ?) branches are near- 

 est the corners of the stomach, while the branches 

 which fuse with the more peripheral parts of the 

 main canals are smaller as we proceed outward. 

 Altogether about 28 centripetal vessels arise from 

 the ring-canal. The 4 main radial-canals are of 

 large caliber, but the centripetal vessels are nar- 

 rower in accordance with their age, the latest 

 formed being narrowest. Dr. H. B. Bigelow has 

 shown that the "side branches " of Maas are actu- 

 ally centripetal vessels which arise from the ring- 

 canal and only later in life join the radial- 

 canals. 



The stomach lacks a peduncle and is narrow 

 and about half as long as the depth of the bell- 

 cavity. It is 4-sided at its base and the 4 lips are 



r n. . 99. fiibogna geometrica, after Maas, in hrgrb. . ' . . _ 



Sibaga Exped., Monog. X. flaring with folded edges. There is a throat-tube 



