AXTIlnMl-.lil ;,.]; KATIIKKA. 



17.') 



Genus RATHKEA Brandt, 1837, sensu Vanhbffen. 



//;icfl, BRANDT, 1837, Bull. Sci.Acad.St.Pftenbouig, nd. i.|>. 1X7; iX;X, Mom. Acatl.Inip.St.Prirn.bnurjvrr.fi. fine 4 .,,.-;-. 



rv/<r/*, in part, SARS, 1835, Beskriv. og Jagttag, p. 28. 



l.izzi.i, FORBES, 1846, Annals anil Mag. Nat. Hist., ser. I, vol. 18, p. 286; 1848, British Naki-d-i-u-d Mrlusa-, p. 64.-- 



CLAPAREDE, 1860, Zeit. fur wissen.Zool., Bd. 10, p. 401, (af. 32, fign. 1-3. AOASSIZ, L., 1862, C.me. Vie. HI-.I. I . s., 



vol. 4, |>. 345. AC;ASSIZ, A., 1865, North Amer. Acal., p. l6l.---\Vv.\t R, ]XS<;, W,rhrl|..M-n .!.-> \V.-i- i-n \|..-r.--. p. 



73. GARSTANI., 1904, Journ. Marine Biol. Association, Plymouth, New Series, vol. -,, p. 213. \U^. iSir. M> m. M'i 



Conip. Zool. at Harvard College, vol. 23, p. 14. HARI.ITT, 1904, Bull. t r . S. Bureau "I 1 i li, n, . \..|. -4. p. 37. 

 Rtahlaa+tfargelllam+Laaaa,Cuu, tXne, Biblmtheta Znnlngica, Hrft 19, l.fg. i, pp. 13, if>, 24, 3/1, tic. 

 Marfrllium, BRUWNE, 1X95, Proc. and Trans. Liverpool Biol. Sot., \ol. </, p. 270; 1896, Proc. Zooi. S,, ( . London. Marftllium, 



p. 477; /.iraia, p. 475. 



Li*u'a+ Liailla+ Margellium-t- Rathkea, HAX-KM, 1X79, Svst. di-r Mi-du .-n, pp. 72, 82, 83, 94, 96. 

 Ralhkfii, LITKF.N, 1850, Vidensk. Mrddel. Nat. r..n-n. Kl"l"-nh.ivn. pp. iX, <;. A..ASMZ, I,., 1X1,2. Cone. Vie. Hit. 1 . s.. vol. 



4. p. 541;. -MtTsc-iiMKOKt, 1886, Embryol. Studien an Mrdu&rn, pp. 23, 37, 48, etc. VANIIOI i i\. 1X91, /.,.!. An/. i l; . i . 



[ahrg. 14, p. 445. 

 Liz:ia RofMea, MAA, e 897, Mem. Museum Comp.Zool.at Harvard C'olli-p'. vol. 23. p. 14; njo5,Cr.isprdotrn Mednsrn dcr Xihaga 



Expedition, Monoj;. 10, p. 12. -Bioor, 1905, Revue Suissc dc Zool., tonic 13, pp. e?7, 144 (illation of references to 1850). 



The type species is Ratliki-n t>l<i>n,-iilin,hii Brandt, of the Black Sea. 1 believe future 

 studies will show that this medusa is identical with Rntlikr/i rjctnpiiiiitntn. 



In 1846-48 Forbes introduced the generic name " Lizziti," applying it to I.IT.ZHI mtn- 

 piiiictntti, which Browne and Garstang have shown to be identical with ('. \t t m in /o/>j//i, tutu 

 of Sars, 1835. 



Haeckel, 1879, defines the following genera: 



Vanhiiffen, 1891, shows that " Lizzia, Margellium, and Ltzzflla" are stages in the growth 

 of Ruthkca. 



Much confusion has thus been introduced by the too narrow definition of genera, as 

 restricted by Haeckel, and it seems well to broaden the genus so as to make it apply to these 

 medusae in all stages of their free lite. 



GENERIC CHARACTERS. 



Margelinae with simple or branched oral tentacles and 8 clusters of marginal tentacles, 

 4 radial and 4 interradial. 



There are perradial, adradial, or interradial gonads on the sides of the stomach and the 

 oral tentacles terminate in knob-like clusters of nematocysts. 



In Rat/ikca medusa-buds are commonly developed upon the sides of the manubiium. 

 Chun, 1895, has shown that these buds are produced entirely from the ectoderm of the parent 

 medusa. A short time before the young medusa is set free, however, a connection is estab- 

 lished between the gastrovascular cavity of the bud and that of the mother medusa. Claparede, 

 1860, describes a "Lizzia" from Scotland in which the embryos are developed upon the outer 

 walls of the stomach very much as is the case with the planulae ot Brmgantvillia superciliaris. 

 In the case of this "Lizzia," however, the eggs, or embryos, are set free inclosed in capsules 

 and then develop directly into medusae. This remarkable observation awaits confirmation. 



According to Browne, 1896 (Proc. Zool. Soc. London, p. 477), the medusa of Lizzm ( Rut liken ) 

 nftnpunftata first reproduces itself by means of medusa-buds upon the_manubnum, and when it 

 reaches the adult condition either ova or spermatozoa develop within the ectodermal wall of 

 the stomach, the sexes being separate; and the same statement applies to Rntlik,-<i hl'inJnifi. 



It is highly probable that the very variable R. oi-topunfttitn is found in the Mediterra- 

 nean and along the Atlantic coasts of Europe and America, and that R. blumenbachii and 

 R. hlnnJiiin are onl snonyms. R. fn.\,-i,-nliil<i is the only known Anthumedusa in which 



the gonads are restricted to the 



sides of the maiuibiium. 



