682 MEDUS.E OF THE WORLD. 



lower half pyramidal and 3-winged, one wing centripetal, the other two centrifugal; outer 

 surfaces of all 3 wings covered with deep furrows which are complexly folded and contain 

 the frilled mouths. A club-shaped, gelatinous appendage arises from the free lower end of 

 each arm and numerous other appendages spring from the sides of the arms between the 

 furrows. No scapulets. 4 horseshoe-shaped gonads. 



The bell-margin and frills of the mouth-arms are deep rose color, while the gonads are 

 paler. This species is found in the tropical Atlantic. 



Size (?) Exact locality (?) A more accurate and modern figure of this form is greatly 

 to be desired for we can not now be certain even of the generic position of this medusa. 



Genus PSEUDORHIZA von Lendenfeld, 1882. 



PituJorhiza, VON LENDENFELD, 1882, Zool. Anzeiger, Bd. 5, p. 380; 1884, Proc. Linnean Soc. New South Wales, vol. 9, p. 293; 

 1887, Descriptive Catalogue Australian Museum, Sydney, part I, p. 23. MAAS, 1903, Scyphomedusen der Siboga Expedi- 

 tion, Monog. II, pp. 53, 71, 80. 



Monorhiza, HAACKE, 1887, Jena Zeit. fiir Naturw., Bd. 20, p. 614. 



The type species is Pseudorhiza aurosa von Lendenfeld, of Victoria and South Australia. 



GENERIC CHARACTERS. 



Rhizostomata tnptera with eight 3-leaved mouth-arms, one or all of which terminates 

 in a single large club. No other clubs or filaments among the mouths. 8 rhopalia. ^radial- 

 canals, 8 rhopalar and 8 adradial. The rhopalar canals extend to the bell-margin, but the 

 adradial ones only to the ring-canal which connects with all of the 16 radial-canals. On the 

 outer side the ring-canal gives off an anastomosing network, and on its inner side a number 

 of blindly-ending, centripetal vessels which may anastomose. The wide, circular muscle 

 of the subumbrella is only partially interrupted in the radii of the radial-canals. The sense- 

 club bears an ocellus and there is a shallow, exumbrella sensory pit without radiating furrows. 

 The central mouth persists at the center of the arm-disk. 



Haacke's genus Monorhiza is similar to Pseudorhiza, but in Monorhiza only one mouth- 

 arm bears a terminal club, whereas all 8 bear each a terminal club in Pseudorhiza. The 

 distinction may be deemed to be of specific rather than of generic value. 



Pseudorhiza is so closely allied to Mastigias that we might readily merge the two genera 

 into one, designating it by the older name Mastigias. In Mastigias, however, one finds small 

 clubs or filaments arising from the sides of the mouth-arms between the mouths, and these are 

 wholly absent in Pseudorhiza; also in Mastigias the inter-rhopalar canals which arise from 

 the inner side of the ring-canal connect with the stomach, whereas in Pseudorhiza they end 

 blindly. These blindly-ending, centripetal canals on the inner side of the ring-canal in Pseu- 

 dorhiza may or may not anastomose. They appear not to anastomose in Haacke's P. haeckelii, 

 but in von Lendenfeld's P. aurosa they are said to form a network; yet von Lendenfeld believes 

 these medusae to be identical, and they are certainly closely related. 



The terminal club in all Rhizostomata is merely the naked extension of the axial shaft 

 of the mouth-arm. It is triangular in cross-section as is the arm itself, and the axial duct of 

 the arm extends onward into it. Thus it is not homologous with the club-like appendages and 

 filaments which arise between the mouth-arms. 



Pseudorhiza aurosa von Lendenfeld. 



Pstudorhiza aurosa, VON LENDENFELD, l88z, Zool. Anzeiger, Bd. 5, p. 380; 1884, Proc. Linnean Soc. New South Wales, vol. 9, 

 p. 293, plate 3, I fig.; Ibid., p. 426. 1887, Descriptive Catalogue Australian Museum, Sydney, Part I, p. 23; 1888, 

 Zeit. fiir wissen Zool., Bd. 47, p. 218, taf. 1 8, fig. I ; taf. 19, fign. 3-7; taf. 20, fign. 14-16; taf. 23, fign. 39, 42, 43, 49-52, 

 57; taf. 24, fign. 60, 62; taf. 26, fign. 84, 87-92, 94, 95; taf. 27, fign. 98-107, 114 (detailed description). 



Umbrella 400 mm. wide, flatly rounded, about 130 mm. high. Exumbrella rough and 

 reticulate. 8 marginal sense-organs and in each octant there are 2 long, narrow, pointed, 

 ocular lappets and 6 velar lappets. Each of the velar lobes consists of 3 secondary lappets. 

 The arm-disk is about as wide as the radius of the umbrella and gives rise to 8 mouth-arms 

 which are about as long as the diameter of the umbrella. There is a central mouth on the 

 (lower) subumbrella side of the arm-disk and 4 pairs (8) of deep gutters extend out from this 



