8EMAEOSTOME i: DE8MONEMA, CTANEA. 



595 



1 he medusa appears to lie common trom December to June in the Antarctic region, ami 

 is reported I'rom Imth sides of the Straits of Magellan, KciiMielcii. and the Falkland Islands; 

 and from Kaiser \\ ilhelm Coast, South Victoria and Alexander I Land along the ice-edge 

 ot the Antarctic continent. 



Ephyrae ^ to IO mm. \\ule are tound in January and February, and Vanhiitten records a 

 young medusa in the M.Jara stage Irom Gauss Station, Kaiser \\ ilhelm Land on April 14. 

 This medusa was }S mm. in diameter, the mouth-arms 10 mm. long. There were 8 principal 

 tentacles about two-thirds as long as bell-diameter, and 4 of these were bordered on one side 

 by a small tentacle ot recent development, figure ^~(). The lips and gastric cirri were 

 brownish-red, other parts being translucent milky-blue. A later stage is descubed by Browne 

 (see figuie $~H |. 



Genus CYANEA P6ron and Lesueur, 1809. 



C\,irii'<i, PV'.KIJX ASI> l.i M i i i:, 1809, Ann. Mir . Hi r. \,it. Paris, tome 14, p. 363. EsCHtCHOLIZ, 1829, Syst. dcr Acalephrn, 

 p. 67. LiasON, 1843, Hist. Zooph.Acal., p. 379. BRAKDT,l838, ' , Si ;. N.ii.. r. i>. tome 



4, p. 77. FORI:>-. iXjs. Itiitish X.iki-,|.i i i 1862, Cont. Nat. Hist. U. S., TO!. 4, pp. 



Id I. An".-.!/. A., lXh v , \. ii lh ATI!, r. \i ,il.. p. 44.-- - VMS l.i MUSI I I I). |SS;, 7j-\\ . fur wisscn . Z')ol., BJ . 37, p. 4d,: 



Proc.Lim South Wall > <; ....... A . K . P., 1900, Mi-m. Ii . .t . Hist., vol. 5, p. 211. 



HARr.irr, C. \\'.. 190:. AnuTHMn N.irur.ili^l. \ "!. ;*' !' ^ N- M A^-'. 1904. Result, t' imp. s < i. I'nrn > .i<- M.m. lt o, ' 

 p. 5;; i >ir>'>. I .1 'in. i \i. lii i. l'.,l. |. I .!';. -,. pp. 4^6. ^o,; MIC;. Si vplniMir.lu i-n .li-r Siboga Expcjitiun, Munog. 1 1, p. 28. 

 VASIH.I>>\, M|od. \'iiji-i h-'- I'l.LiiLrnn. \i. 11. p. ^i. 

 Proc\anra+ M(doru + Slrnoptv<:ha+ Drsmontma (tn .-:r,i. \\ \n k'l.i., 1880, Syit. d'-r Mt-Jubtn, pp. 524-528. 



The type species is C. ciifiillitn of the North Atlantic. Pacific, and Arctic Oceans. It is 

 the largest of all known medusae. 



GENKKIC CHARACTKRS. 



Cyaneidae with 8 marginal sense- 



oigans and with 8 adradial crescentic 

 groups ot tentacles. Each group consists 

 of several rows of tentacles. With radial 

 muscle strands in the subumbrella. 



When young only 8 simple tentacles 

 arise in the adradial clefts between the 

 ephyra lobes, bur later the margin grows 

 beyond them, leaving them to project trom 

 the floor of the subumbrella. In the mean- 

 time the tentacles increase in number, 



iinng a row in each adradius, but 

 finally they come to lie in two or more 

 rows, llaeckel has constituted a special 

 genus tor each of these growth-stages. 

 He calls the 8-tentaclcd stage "/YoryaM, -ii." 

 The stage with 24 tentacles, 3 in each 

 adradius, he names "Medora" and when 

 then- are 5 tentacles in each row the medusa 

 becomes a " Si, -ii'if't \, li,i" ; then as long as 

 the medusa remains with the tentacles of 

 each cluster in a single ro\v it is a " Des- 

 mi,n,-tnn" and finally when older and the 

 tentacles begin to develop in two or more 

 K>\\s in each cluster the medusa is called a 

 C.viini'it. It is possible that some medus;r 

 nia\ become marine in, and never advance 

 beyond, llacckil's " Desmonema stage, 



onema chitrchiana. 

 FIG. 378. After Browne, in Trans. Royal. Soc. Edinburgh. 



F.c. 379.- Young medusa, afta Vanhoffen in deutsch. Siidpolai l> ut j t j s certain that others pass through this 



Expedition. 



condition and become mature as C.\<inf>i. 



Medusae of C:\,in, ,i are abundant in the Arctic and Antarctic, but are not found in the 

 tropics. Being dependent upon a fixed scyphostoma-stagc tor development, they are confined 

 to the proximity of coasts where the water is relatively shallow. 



