RHIZOSTOMxE — RHIZOSTOMA. 703 



Rhizostoma pulmo var. lutea Eschscholtz. 



Orilhyla lutea, Quov et Gaimard, 1827, Annal. ilcs Sci. Nat., Zool., tome 10, p. 175, planchc 4B, fig. I. 

 Rhizostoma lutea, Eschscholtz, 1829, Syst. der .Acaleplicn, p. 51. 

 Pilema stylonectes, Haeckel, 1880, Syst. der Mcdusen, p. 595. 



Rhizoitoma luteum, Vanhoffin, 188S, Bibliothcca Zoologica, Bd. I, Ht-ft. 5, p. 43.— Grenacher und Noll, 1876, Abliandl. 

 Senckenberg Naturforsch. GescU., Bd. 10, p. 42, taf. 8. 



See the tabular synopsis of species of Rhizostoma. 



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

 between R. pulmo 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 he 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. 



Urtka marina, etc., octopeJalis, Borlase, 1758, Nat. Hist, of Cornwall, p. 258, plate 25, figs. 15-17. 



Medusa octopus, Linne (Gmelin), 1788, Systema Natural, Ed. 13, Pars. 6, p. 3157. 



Medusa hleu, CcviER, 1799, Journal de Physique, Chimie, d'Hist. Nat. ct des Arts, Paris, tome 49, p. 437, I planchc. 



Cassiapea borlasea+ Rhizostoma cuvieri, Peron et Lesueur, 1809, .\nnal. du Mus. Hist. Nat. Paris, tome 14, pp. 357, 362. 



Cassiopea lunulata, Eschscholtz, 1829, Syst. der .Acalephen, p. 44. 



Rhyzostoma octopus, Oken, 1835, AUgemeine Naturgesch., Bd. 5, p. 218. 



Cassiopea anglica+C. rhizostomoidea+ Rhizostoma sepioides, Tilesius, 1829, Nova Acta .Acad. Cur., Leop. C, tome 15, pp. 273, 

 283, tab. 71. 



Rhizostoma coeruleum, Cuvier, 1817, Regne .\nimal., tome 4, p. 57. 



HoligQcladodes lunulatus, AcASSlz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 155. 



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



Rhizostoma octopus, Vanhoffen, 1888, Bibliothcca Zoologica, Bd. I, Heft. 3, p. 43; 1906, Nordisches Plankton .Acraspede Mcdus., 

 Nr. II, p.63,iign.33, 34J 1908, deutsche Siidpolar Exped., 1901-03, Bd. 10, Zool. 2, pp. 28, 47. — Dahl, 1893, Kommiss. zur 

 wissenschaft. Untersuch. deutsch, MeereKiel, Ber.6, p. 172. — Browne, 1905, Proc. Roy. Soc. Edinburgh, vol. 25, p. 776. 



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

 cold waters ot the Atlantic coasts of Europe, being found off the shores of 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, 3-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 eph\ra, 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 

 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. 



Medusa corona, Forsk.^l, 1775, Descript. .Anim. Itin. Orient., p. 107. 



Rhizostoma corona, Eschscholtz, 1829, .Syst. der .Acal., p. 52. — Vanhoffen, 1888, Bibliotheca Zoologica, Bd. I, Heft. 3, p. 43. 



Rhizostoma cuvieri, Ehrenrerg, 1835, Abhandl. Berlin .Acad., p. 184. 



Pilema corona, H.aeckel, 1880, Syst. der Medusen, p. 594. 



See synoptic table of the species of Rhizostoma. 



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

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

 instead of 80 as in R. pulmo. 



Rhizostoma pulmo var. capensis Lesson. 



Cephea capensis, Quov et Gaimard, 1824, Voyage dc VUranie, p. 568, planche 84, fig. 9. 



Rhizostoma capensis, Lesson, 1843, Hist. Zooph. Acalephes, p. 417. 



Pilema capcnse, Haeckel, E., 1880, Syst. der Medusen, p. 645. 



Rhizostoma capense, Vanhoffen, 1888, Bibliotheca Zoologica, Bd. 1, Heft. 3, p. 43. 



