RHI/USTiiM.K HIIIZIISTUMA. 703 



Rhizostoma pulrao var. lutea Eschscholtz. 



Orithvia lutea, Qtiov tT GAIMARD, 1827, Anna), dc^ Sn. Nat., Zool., tome 10, p. 175, planche 48, fig. I. 

 Rhizostoma lutea, ESCHSCHOLTZ, 1829, Syst. dor Acalephen, p. 51. 

 Pilema stylonectes, HAECKF.L, 1880, Syst. der Mrdusen, p. 595. 



Rhizostoma hileum, VANHUFFF.N, 1888, Bibliotheca Zoologica, Hil. I, Heft. ;, p. 4;. <;K>\M it t R UNO NOLL, 1876, Abhandl. 

 Senckcnberg Naturforsch. Gesell., Bd. 10, p. 42, taf. 8. 



See the tabular synopsis of species of Rlitzostomn. 



This medusa, from the Straits of Gibraltar, is intermediate in most of its characters 

 between R. pultun of the Mediterranean and R. octopus of the Atlantic coasts of Europe. 

 Indeed the 3 forms are so closely related that we may consider them to be local varieties 

 one of another. R. lutea is distinguished chiefly by its very long, terminal appendages on the 

 mouth-arms. 



Rhizostoma pulmo var. octopus Oken. 



I 'nil a m, ir inn, fir., octopedalis, BORLASK, 1758, Nat. Hist, of Cornwall, p. 258, plate 25, figs. 15-17. 



Medusa octopus, LINNE (Gmelin), 1788, Systema Natura-, Ed. 15, Pars. 6, p. 3157. 



Medusa bleu, CI'VIF.R, 1799, Journal de Pli\^ii|Ui i , C'himir, d'Hi^t. N.u. ct drs Arts, Paris, form- 49, p. 437, I planche. 



Cassiopea borlasea+ Rhizostoma curieri, PERON FT LIM n K, 1809, Annal. du Mus. Hist. Nat. Paris, ionic 14, pp. 357, 362. 



Cassiopea lunulata, ESCHSCHOLTZ, 1829, Syst. di-r Acah-phcn, p. 44. 



Rhvzostoma octopus, OKEN, 1835, Allgcmcine Naturgesch., Bd. 5, p. 218. 



Cassiopca angliea+C. rhizoslomoidea+ Rhizostoma sepioidcs, TILESIUS, 1829, Nova Acta Acad. Cur., Leop. C., tome 15, pp. 273, 

 283:, tab. 71. 



Rhizostoma cocrultutn, CI'VIER, 1817, Regnc Animal., tome 4, p. 57. 



Holigocladodes lunulatus, ACASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 155. 



Pilema octopus, HAF.CKEL, 1880, Syst. der Meduscn, p. 593 (list of authors). 



Rhizostoma octopus, VANHOFFKN, 1888, Bibliotheca Zoologica, Bd. I, Heft. 3, p. 43; 1906, Nordisches Plankton Acraspcde Medus., 

 Nr. II, p.63,fign. 33,34; 1908, deutsche Siidpolar Expcd., 1 901 -03, Bd. lo, Zool.2, pp. 28, 47. DAHL, 1893, Kommiss. zur 

 wissenschaft. Untersuch. deutsch, Mcerc Kiel, Bcr. 6, p. 172. BROWNE, 1905, Proc. Roy. Soc. Edinburgh, vol. 15, p. 776. 



This form is closely allied to R. pulmo of the Mediterranean, but it ranges into the 

 cold waters of the Atlantic coasts of Europe, being found off the shores ot France, England, 

 Scotland, Belgium, Holland, and Germany. Mature individuals occur in great swarms in 

 September and October and are often cast ashore in vast numbers. The medusa differs 

 from R. pulmo in having 96 to 112 marginal lappets instead of 80. The lappets are more 

 pointed than in R. pulmo. The simple, upper part of the arm is shorter than the lower, ^-winged 

 part, whereas in the typical R. pulmo the reverse is usually the case. The terminal clubs are 

 widest near their outer ends, whereas in R. pulmo they are widest near their bases. In other 

 respects it appears to be identical with R. pulmo. 



Vanhoffen, 1906, describes the young ephyra, 3 mm. wide, in the stage wherein the 4 rays 

 of the cruciform, central mouth are beginning to fork at their outer ends. There are 4 small 



o o 



clusters of gastric cirri. 16 radial-canals. The 8 rhopalar radial-canals extend to the marginal 

 sense-clubs and the 8 adradial canals end in the ring-canal, which is at a considerable distance 

 inward from the bell-margin. This ephyra is thus similar in all respects to that ot R. pulmo. 

 It is somewhat remarkable that R. octopus is not found among the Azores, Canaries, or 

 other island groups of the Atlantic. Borlase states that in 1758 it was sometimes eaten by 

 man in Cornwall. 



Rhizostoma pulmo var. corona Eschscholtz. 



Mfdtistt corona, FORSKAL, 1775, Descript. Anim. Ttin. Orient., p. 107. 



Rhizostoma corona, ESCHSCHOI.TZ, 1829, Svst. der Acal., p. 52. VANHIIFFEN, 1888, Bibliothcca 7xlogic.i, Bd. I, H.-ft. ',. p. 43. 



Rhizostoma cuvieri, EHRF.NBERG, 1835, Abhandl. Berlin Acad., p. 184. 



Pilrma corona, HAECKF.L, 1880, Syst. der Meduscn, p. 594. 



See synoptic table of the species of Rhizostoma. 



This imperfectly known Red Sea medusa appears to be closely related to R. pulmo of the 

 Mediterranean, but is said to be distinguished by having 140 to 180 marginal lappus. 

 instead of 80 as in R. pulmo. 



Rhizostoma pulmo var. capensis Lesson. 



Cephea capensis, QUOY IT GAIMARD, 1824, Voyage de Vl'ranie, p. 568, planche 84, fig. 9. 



Rhizostoma capensis, LESSON, 1843, Hist. Zooph. Acaiephes, p. 417. 



Pilema capense, HAECKEL, E., 1880, Syst. der Mt-.lu-i-n, p. 64^. 



Rhizostoma capense, VANHOFFEN, 1888, Bibliothcca Zoologica, Bd. i, Heft. 3, p. 43. 



