678 



MEDUS.E OF THE WORLD. 



of the mouth-arms in addition to the terminal club, I have merged it with Mastigias for the 

 genera among R/uzostotnata triptera are already too numerous, and are distinguished upon 

 differences of such slight imponance that the distinctions threaten to confuse rather than u> 

 clarify the system of classification. 



Mastigias is closely allied to Pscudorhiza, but may be distinguished by its numerous, 

 complete, interocular radial-canals; whereas the converging vessels on the inner side of the 

 ring-canal between the 16 radial-canals in Pseudorhiza end blindly without reaching the 

 stomach. 



The canal-system of von Lendenteld's Ph \llor hi%a puiifttita is similar to that of Mastigias, 

 but the mouth-arms bear numerous very long filaments without any definite terminal club. 



The following synopsis of the forms of Alastioias may be of service, r is the length of 

 the radius of the exumbrella. 



Tabular Synopsis of the Forms of Mastigias. 



Mastigias papua L. Agassiz. 



Cepliea papua, LESSON, 1829, Voyage de la Coquille, Zooph., p. 122, planche 11, figs. 2, 3. 



Cephta papuensis, GRIFFITH, 1832, Cuvier's Animal Kingdom, plate 3, fig. 3. 



Mastigias papua, AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 152. HAECKEL, 1880, Syst. der Medusen, p. 623. MAAS, 



1903, Scyphomedusen der Siboga Expedition, Monog. 1 1, pp. 66, 69, taf. 7, fign. 60, 62, 63; taf. 12, fig. 1 1 1 . 

 Psfudorhiza thocambaut, AGASSIZ, A., and MAYER, 1899, Bull. Museum. Comp. Zool. at Harvard College, vol. 32, p. 173, plate 



13, figs. 40-44 (young stages). 

 Maslygias papua, VANHOFFEN, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Valdivia, Bd. 3, Lfg. i, p. 47, taf. 4, fign. 



17-19. 

 Masttgtas physophora, KISHINOUYE, 1895, Zoolog. Magazine, Tokyo, vol. 7, No. 78, 3 pp., plate 13, figs. 1-13. SCHULTZE, L. S., 



1898, Denkschr. Med. Nat. Gesell. Jena, Bd. 8, p. 443. 



Mastigias physophora, VANHOFFEN, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Dampfer Valdivia, Bd. 3, Lfg. I, p. 49. 

 Mastigias papua var. ph\sophora, MAAS, 1909, Abhandl. Akad. Wissen. Miinchen, Suppl. Bd. I, Abhandl. 8, p. 46. 



Bell 30 to 80 mm. wide, usually hemispherical, sometimes flatter and sometimes fuller 

 than a hemisphere. Gelatinous substance firm. Exumbrella surface with very fine granu- 

 lations. 8 rhopalia, each with a pigmented mass of crystalline concretions and a shallow, 

 exumbrella, sensory pit without furrows. 80 marginal lappets. In each octant 2 small, 

 pointed, ocular and 8 larger, rounded velar lappets with deep furrows between them extending 

 a short distance up the sides of the exumbrella. Arm-disk somewhat wider than bell-radius. 

 The 4 subgenital ostia are about twice as wide as the columns between them and are each 

 somewhat constricted in the middle. Subgenital porticus unitary. 8 mouth-arms, each about 

 as long as bell-radius. The simple upper part 1.5 times as long as the 3-winged lower portion 

 of the arm. The frilled mouths are developed not only along the edges of the 3 wings, but also 

 for some distance inward along the sides of each leaf. Each mouth-arm usually terminates 

 at its lower end in a club-like filament which may be as long as the diameter of the bell, but 

 is sometimes reduced in size or even wholly absent. This club is triangular in cross-section 

 and contains an axial canal. A large number of small, club-shaped vesicles arise from between 



