546 



MEDUS.E OF THE WORLD. 



into the i6 marginal lappets. A partial septum extends, however, down the midline of each 

 lappet, and the gastro\ascular 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 V'anhiJffen's figure 3, taf. i, in " Ergeb. 

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



The inner surface of the subumbrella is purple, while the pedalia 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 

 Nonh .Xtlantic. It has been taken in the Ba\- of Biscay; at the Azores; off Cape Hatteras, 

 North Carolina; at Manha'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 I'aUitvia found it m both the Atlantic 

 and Indian Oceans. The best descriptions are those of Vanhijffen 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 ol such great size. 



Periphylla hyacinthina forma dodecabostrycha. 



Chrysaora {dodecabostrycha) dubia, Brandt, 183S, Mt-m. .\cad. Sci. St. Pt-ler.^bourg, .Sci. Nat., ser. 6, tome 4, p. 387, taf. 29, 30. 

 Periphylla dodecaboitrycha, Haeckel, 1880, Syst. der Meduscn, p. 421. — VANHiitUN, 1892, Ergeb. der Plankton Exped., Bd. 1, 



K.d., taf. 2, fign. 1,2; 1908, deutsche Siidpolar Expedition 1901 -1903, Bd. 10, Zoo). 2, p. 35; i902,\Vissen. Ergeb. deutsch. 



Tiefsee Expcd., Valdivia^ Bd. 3, pp. 21, 23. — Maas, 1903, Scyphomedusen der Siboga Expedition, Monog. 1 1, 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 Han-ard College, vol. 23, p. 64, taf. 1 1, 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 Paraphyllina). 

 (?) 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 usuall\' be seen through the gelatinous walls ot 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. hvacinthmn, and the hell-walls are more transparent. 



Widely distributed over the floor ot the 

 great oceans, and especially in tropical parts of 

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

 Hawaiian Islands, Philippine Islands, liulian 

 Ocean, Malay Archipelago, Mediterranean, 

 Guinea Stream oft' Atlantic coast of Africa-. 



It is probably only a variety of, or even 

 onl\- a growth-stage of, P. hyacinthina. 



Periphylla hyacinthina forma regina. 



Periphylla reginOf Haeckel, 1880, Syst. der Mcdusen, p. 421; 

 1881, Deep-sea Medusa? 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, 

 1 fig.; 1903, Scyphomedusen Siboga Exped., p. 6. — Van- 

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

 Faldivia, Bd. 3, Lief. 1, pp. 21, 23; 1908, deutsche Siid- 

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



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

 1881, C/i/2//e«^er Exped. Report, Zool., vol. 4, p. 64, plates 

 18-23, 40 figs- 



Fig. 344. — Periph\lla regina, after VanhofTcn, in 

 Tiefsee Expedition Valdivia. 



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 

 nearly 1.5 times as wide as high, but Haeckel 



