402 MEDUSA OF THE WORLD. 



GENERIC CHARACTERS. 



Aglaurinae with 8 gonads situated upon the 8 radial-canals. These gonads are attached 

 to the subumbrella, or to the zone between the subumbrella and the peduncle; not situated 

 upon the peduncle as in Aglaura. The medusae are not hermaphroditic as in Amphogona 

 Browne. 



Haeckel distinguishes Aglantha with 4 and Agliscra with 16 lithocyst-clubs. 



The common Aglantha digitale of the New England coast is, however, very variable in 

 the number of its sensory-clubs, ranging in specimens observed by me from 3 to 8. More- 

 over, these clubs are very readily lost and appear to be too variable, even when present, to 

 afford suitable data for generic distinctions, and it would seem desirable to unite the above 

 genera under the name Aglantha. 



Maas, 1893, distinguishes Aglantha with 8 gonads upon the turning points in the 8 radial- 

 canals between the peduncle and the subumbrella; and Agliscra with gonads upon the sub- 

 umbrella. It is, however, a difficult matter to decide whether the gonads are upon the 

 subumbrella or upon the turning points of the canals at the base of the peduncle. More- 

 over, such a classification would in my opinion unduly restrict the genus Aglantha. The 

 exact position of the 8 gonads, on the other hand, provides us with a ready means of distin- 

 guishing species one from another. 



Vanhoffen, 1902 ( Valdivia, Bd. 3, Lfg. I, p. 76) would amend Haeckel's Agliscra to include 

 Aglauridae with 8 linear gonads attached throughout their lengths, not merely suspended from 

 the 8 radial-canals. There are, however, species or varieties of Aglantha with globular, neither 

 suspended nor sausage-shaped, gonads, and when young the medusae of Aglantha digitale 

 have linear gonads. Moreover, Haeckel's type species of Agliscra has suspended, sausage- 

 shaped gonads. 



Aglantha is closely related to Aglaura, but in the latter genus the 8 gonads are developed 

 upon the 8 radial-canals on the peduncle above the stomach. 



Amphogona Browne is doubtfully distinguished by its being said to be hermaphroditic, 4 

 of the radial-canals bearing male gonads and the 4 canals which alternate with them bearing 

 female genital organs (see Bigelow, 1909, p. 126). 



Aglantha digitale Haeckel. 



Plate 49, figs. 2 and 2'. 



Digitate (mfrfu5fl),MULLER, O.F., 1766, Prodrora. Zool.Dan., p. 233, No. 2824.— Fabricius, 1870, Fauna Gronlandica, p. 366, 

 No. 361. 



Melicerta digitale, Peron et Lesueur, 1809, Ann. Mus. Hist. Nat. Paris, tome 14, p. 352, No. 72. 



Diatnea digitale, Lamarck, 1817, Anim. sans Vert., tome 2, p. 507. 



Eirene digitale, Eschscholtz, 1829, Syst. der Acalephen, p. 95- 



Turrit borealis, Lesson, 1843. Hist. Zooph. Acal., p. 284. 



Circe rosea, Forbes, 1848, British Naked-eyed Medusae, p. 34, plate i, fig. 2.— Agassiz, L., 1862, Cont. Nat. Hist. U. *., vol. 

 4, p. 349. 



Turrit (Circe) digitalis, Morch, 1857, Beskriv af Gronland, p. 95. 



Trachynema digitale, Agassiz, A., 1865, North Amer. Acalepha:, p. 57, figs. 81-86. 



Circelia digitalis, Haeckel, 1877, Prodrom. Syst. der Medusen, No. 287 (unpublished). 



Aglantha digitalis, Haeckel, 1879, Syst. der Medusen, p. 272, taf. 16, fign. 5, 6.-Hartlaub, 1894, Coelenteraten Helgoland*, 

 Meeresfauna von Helgoland, p. 197, Kiel und Leipzig— Fowler, 1899, Proc Zool. Soc. London, p. 1031.— Maas, 1891, 

 Sitzungsber. Akad. Wissen. Berlin, p. 336; 1893, Ergeb. der Plankton Exped., Bd. 2, K. c, pp. 23, 24.— Harc.itt, 1904, 

 Bull. IT. S. Bureau of Fisheries, vol. 24, p. 55, I fig.; 1902, young medusa, Aglantha conica, Biol. Bulletin \\ oods Hole, 

 vol. 4, p. 21, fig. 7; Ibid., vol. 14, p. in— Vanhoffen, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Dampfer 

 Valdivia, Bd. 3, Lfg. 1, p. 78.— Maas, 1906, Fauna Arctica, Bd. 4, Lfg. 3, p. 1509 (review of literature). 



Trachynema digitale, Fewkes, 18S1, Bull. Mus. Comp. Zool. at Harvard College, vol. 8, No. 8, p. 160, plate 2, figs. 5, 6.-Nlt- 

 tinc, 1901, Bull. U. S. Fish Commission, vol. 19, p. 381, fig. 102. 



( ?) Aglantha rosea, Browne, 1898, Proc. Zool. Soc. London for 1897, p. 833, plate 49, figs. 1., In, li. 



Aglantha rosea+A. digitalis, Browne, 1903, Bergens Museums Aarbog, No. 4, pp. 22, 23. 



Aglantha rosea, Browne, Trans. Linnean Soc. London, ser. 2, Zool., vol. 10, p. 175.— Fowler, Ibid., p. 182— Gunthfr, 1903, 

 Annals and Mag. Nat. Hist., ser. 7, vol. 11, p. 427, plate 10, figs. 6-8. 



Circe camtschatica, Brandt, 1838, Mem. Acad. Sci. St. Petersbourg, ser. 6, torn. 4, p. 354, planche 1, figs. 1-5 (coast of Kamt- 



schatka). . . 



Trachynema camtschatica, Agassiz, A., 1865, North Amer. Acal., p. 55, figs. 76-80 (from Gulf of Georgia, Pacific). 



Adult medusa (plate 49, fig. 2).— Bell about 30 mm. in height, 15 mm. in diameter; bell- 

 walls are extremely thin, but quite rigid, so that swimming is accomplished by means of the 

 pulsations of the large and powerful velum. The bell terminates in a small, solid, conical 



