PTYCHOGENA. 



217 



Linko also considers Ptychogena to be a deep-sea form; as Browne, 1907, and Bigelow, 

 1909, state, however, we have no trustworthy evidence upon this point and it is not improb- 

 able that the medusa is merely a rare and somewhat variable Arctic species which lives 

 constantly at or near the surface. 



Ptychogena longigona Maas. 



Plychogcna longigona, MAAS, 1893, Ergeb. der Plankton Eiped., Bd. 2, K. c., pp. 64, 97, taf. 6, fign. 7-9. 

 Plychogena ( ?) longigona, BROWNE, 1907, Annals and Mag. Nat. Hist., scr. 7, vol. 10, p. 474. 



Bell 25 mm. wide, flat, with firm gelatinous substance. About 100 tentacles very closely 

 set side by side so that they form an outer row around the margin, on the outer side of which 

 is a row of marginal clubs. Circular canal simple, but the 4 wide radial-canals have numerous, 

 indistinct, unbranched diverticula along their sides, the spaces between the lateral branches of 

 the canals being nearly rilled in by the gonads. Stomach shallow and 4-cornered and about 

 one-fourth as wide as the diameter of the bell. The mouth is a wide cruciform opening with 

 lips turned back as in Ptychogena, so that the water may enter the wide openings of the 4 

 radial-canals at the corners of the stomach. The gonads cover the entire lengths of the 4 

 radial-canals and their lateral surfaces give rise to hollow, evaginated, sac-like elevations or 

 papillae, which are neither so complex nor so regularly arranged as in Ptychogena. These 



papillae occur along either side of each radial- 

 canal, but not in the median line. The mature 

 genital products are in the ectoderm. The 

 grooves of the 4 radial-canals extend along the 

 upper wall of the stomach and meet in the middle. 

 Color ( ?) 



The species was found by the Plankton 

 expedition in the North Atlantic at a depth of 100 

 to 200 fathoms, but Maas does not give the exact 

 locality. As he states, it may prove to be only a 

 local variety of Ptychogena pinniilnin (Inctea). 

 It differs from Ptychogena I/itten, however, in 

 the simple side branches upon the radial-canals 

 and in that the gonads extend along the entire 

 length of the sides of the radial-canals, not being 

 restricted to their middle parts as in Ptychogfnu 

 lactea. The hollow elevations upon the gonads 

 are also simple and not so regularly arranged 

 as in P. lactea. 



Medusae somewhat similar to P. longigona were found by the Plankton expedition near 

 the Cape Verde Islands. 



Ptychogena? antarctica Browne. 

 Ptychogena antarctica, BROWNE, 1907, Annals and Mag. Nat. Hist., vol 20, ser. 7, p. 474. 



The basal bulbs of the tentacles are laterally compressed and without ocelli. They resem- 

 ble those of P. lactea. Number of tentacles( ?) Sensory-clubs( ?) The 4 radial-canals have 

 wavy outlines, but no lateral branches. The wavy outlines of the radial-canals correspond with 

 those of the gonads, which are broad, lateral folds extending only part way along the radial- 

 canals. The stomach was lost in the single specimen studied by Browne. The tentacles are 

 red. Size of medusa( ?) 



Found off Cape Andre, Victoria Land, Antarctic Ocean. 



Ptychogena erythrogonon Bigelow. 



Ptychogena erythrogonon, Bir.Et.ow, H. B., 1909, Bull. Mus. Comp.Zool. at Harvard College, vol. 57, p. 150, plates 5, 38, and 39. 



This medusa is beautifully figured and well described by Bigelow. 



Bell 38 mm. wide, 25 mm. high with very thick gelatinous substance and shallow bell- 

 cavity. 40 to 60 tentacles about one-fourth as long as bell-diameter and with tapering, 

 conical basal bulbs. There are only a very few cirri between the tentacles and these ter- 



Fic. 110. Ptychogena longigona, after Maas, in 

 Ergeb. Plankton Expedition. 



