546 



MEDUSA OF THE WORLD. 



into the 16 marginal lappets. A partial septum extends, however, down the midline of each 

 lappet, and the gastrovascular space forms a marginal ring-canal around these septa. Diver- 

 ticula of the annular space also extend for a short distance into the bases of the tentacles, 

 but the main entodermal cores of the tentacles are solid. A good idea of the structure of the 

 gastrovascular cavity of the bell may be obtained from Vanhoffen's figure 3, taf. i, in "Ergeb. 

 der Plankton Expedition," Bd. 2, K. d. 



The inner surface of the subumbrella is purple, while the pedaha are copper-brown 

 colored and the tentacles and lappets are of a milky-blue translucency. The gonads can 

 not be seen through the densely pigmented bell-walls. 



This deep-sea medusa is occasionally found upon the surface in the colder parts of the 

 North Atlantic. It has been taken in the Bay of Biscay; at the Azores; off Cape Hatteras, 

 North Carolina; at Martha's Vineyard; at Spitzbergen, and still more commonly off the 

 coast of Greenland, but its true habitat is undoubtedly in the deep sea, at or near the bottom. 

 Nearly all recent deep-sea expeditions record it, and the Valdivia found it in both the Atlantic 

 and Indian Oceans. The best descriptions are those of Vanhoffen and Maas. 



Haeckel states that the bell of this medusa may become 160 mm. high and 120 mm. 

 wide, but later observers have not seen specimens of such great size. 



Periphylla hyacinthina forma dodecabostrycha. 



Chrysaora (dodecabostrycha) dubia, BRANDT, 1838, Mem. Acad. Sci. St. Petersbourg, Sci. Nat., ser. 6, tome 4, p. 387, taf. 29, 30. 

 Periphylla dodecabostrycha, HAECKEL, 1880, Syst. der Medusen, p. 421. VANHOFFEN, 1892, Ergeb. der Plankton Exped., Bd. 2, 



K.d., taf. 2, fign. 1,2; 1908, deutsche Sudpolar Expedition 1901-1903, Bd. 10, Zool. 2, p. 35; 1902, Wissen. Ergeb. deutsch. 



Tiefsee Exped., Valdivia, Bd. 3, pp. 21, 23. MAAS, 1903, Scyphomedusen der Siboga Expedition, Monog. II, p. 6, taf. 2, 



fig. 15; taf. 12, fig. 107 (figure of rhopalium); 1904, Result. Camp. Sci. Prince de Monaco, fasc. 28, p. 47, planche 5, figs. 



36, 37; 1897, Mem. Mus. Comp. Zool. at Harvard College, vol. 23, p. 64, taf. u, fig. i. MAYER, 1906, Bull. U. S. Fish 



Commiss. for 1903, vol. 23, part 3, p. 1136, plate 3, figs. 5, 6. 



non Periphylla dodecabostrycha, LOBIANCO, 1903, Mitth. Zool. Sta. Neapel, Bd. 16, p. 219, taf. 7, fig. 3 (this is a Paraphyllitta). 

 ( ?) Periphylla humilis, FEWKES, 1886, Report Commiss. Fish and Fisheries U. S. A., for 1884, p. 931. 



Bell higher than wide in young, wider than high in well-grown medusae. Thus when the 

 medusa is 50 mm. wide the bell is 55 mm. high; when 45 mm. wide it is 45 high; and when 

 100 mm. wide it is 70 mm. high. 



The gonads may usually be seen through the gelatinous walls of the bell, but not so 

 clearly in old as in young specimens. Thus the bell is said to be lower, flatter, and less pointed 

 than in P. hyacinthina, and the bell-walls are more transparent. 



Widely distributed over the floor of the 

 great oceans, and especially in tropical parts of 

 the Pacific, west coast of Mexico, coast of Chile, 

 Hawaiian Islands, Philippine Islands, Indian 

 Ocean, Malay Archipelago, Mediterranean, 

 Guinea Stream ofF Atlantic coast of Africa. 



It is probably only a variety of, or even 

 only a growth-stage of, P. hyacinthina. 



Periphylla hyacinthina forma regina. 



Periphylla regina, HAECKEL, 1880, Syst. der Medusen, p. 421; 

 1881, Deep-sea Medusx Challenger Exped. Report, Zool., 

 vol. 4, p. 85, plates 24, 25. MAAS, 1897, Mem. Museum. 

 Comp. Zool. at Harvard College, vol. 21, pp. 29, 64, taf. 10, 

 i fig.; 1903, Scyphomedusen Siboga Exped., p. 6. VAN- 

 HOFFEN, 1902, Wissen. Ergeb. deutsch. Tiefsee Exped., 

 Valdivia, Bd. 3, Lief. I, pp. 21, 23; 1908, deutsche Sud- 

 polar Expedition, 1901-1903, Bd. 10, Zool. 2, p. 36. 



Periphylla mirabilis, HAECKEL, 1880, Syst. der Medusen, p. 442; 

 1881, Challenger Exped. Report, Zool., vol. 4, p. 64, plates 

 18-23, 4 fiS s - 



This appears to be merely a light violet or 

 rusty-reddish variety of P. hyacinthina. Bell 

 usually low, dome-like, about i 50 mm. wide, and 



rio. 344. Periphylla regina, after Vanhoffen, in . ; I-IITTII 



Tiefsee Expedition Valdivia. nearly 1.5 times as wide as high, but Haeckel 



