228 



OF THE WORLD. 



Were it not for the absence of ocelli I would be inclined to regard this medusa as a 

 hypertrophic specimen of Staurodiscus tetrastaurus in which the side branches of the 4 

 primary radial-canals had reached the circular vessel and 4 intermediate canals had 

 developed. I have, however, never observed such a condition among many hundreds of 

 apparently mature medusas of S. tetrastaurus found at Tortugas, Florida ; and it seems 

 probable therefore that Professor Brooks's medusa is a new species which may have been 

 derived from a Staurodiscus-like ancestor. 



Genus TOXORCHIS Haeckel, 1879, sens. ampl. 



Toxorchii + Cladocanna, HAECKEL, 1879, Syst. der Medusen, pp. 156, 160. 



Toxorcliis, MAAS, 1904, Sitzungsber. math.-phys. Klasse kgl. Bayer. Akad. Wissenschaft., Bd. 34, p. 441. 



Haeckel, 1879, founded this genus for Toxorchis arcuatus of the Canary Islands, Atlantic 

 Ocean; but the first known species is T. thalassina=Berenix tluilnssina Peron and Lesueur, 

 1809, from Northern Australia. 



GENERIC CHARACTERS. 



Thaumantiadae with 4, 6, or more main radial-canals which branch regularly and dichot- 

 omously one or more times. The gonads are upon the outermost branches of the radial-canals, 

 near the ring-canal. Numerous tentacles, cirri, and marginal clubs. Hydroid unknown. 



Haeckel restricts Toxorchis to include medusae having radial-canals branched once 

 dichotomously, while his Cladocanna applies to medusae having radial-canals with 2 or more 

 dichotomous branchings. 



Toxorchis thalassina Maas. 



Berenix lhalassina, PERON ET LESUEUR, 1809, Annal. du Mus. Hist. Nat. Paris, tome 14, p. 327. 



Berenice euchroma, DE BLAINVILLE, 1834, ManXiel d'Actinologie, p. 276, plate 32, fig. I. 



Cm'ieria euchroma, LESUEUR, 1839, m Cuvier's Le Regne animal, plate 53, fig. 2. 



Cladocanna thalassina+ C. pol\clada, HAECKEL, 1879, Syst. der Medusen, pp. 160, 161. 



Cladocanna polyclaiia, YON LENDENFELD, 1884, Proc. Linnean Soc. N. S. Wales, vol. 9, p. 581. 



Toxorchis thaiassiria, MAAS, 1904, Sitzungsber. math.-phys. Kla&se kgl. Bayer. Akad. Wissenschaft., Bd. 34, p. 441. 



Cladocanna thalassina, BEDOT, 1901, Revue Suisse de Zool., tome 9, p. 482; Ibid., 1905, tome 13, p. 132 (list of papers to 1850). 



Bell flatter than a hemisphere to hemispherical, about 50 mm. wide. About 100 or more 

 long tentacles with marginal clubs and cirri between them. Stomach shallow, with 6 wide lips. 

 6 wide radial-canals arise from stomach. For one-third the distance between stomach and 

 margin these canals are simple and unbranched, but outwardly they branch dichotomously 

 and somewhat irregularly 3 to 4 times, so that there are about 100 terminal branches which 

 reach the circular canal at the margin. The sac-like, spindle-shaped, folded gonads are 

 developed upon the outermost branches of canals. The entire medusa is light sea-green. 



Found off the coasts of New Guinea and 

 Northern Australia. Development unknown. 



Toxorchis arcuatus Haeckel. 



Toxorchis arcuatus, HAECKEL, 1879, Syst. der Medusen, p. 157, 

 taf. 9, figs. 6-8. 



Bell flat to hemispherical, 6 mm. wide. 

 Stomach small and flat, with 6 much crinkled, 

 lanceolate lips. 6 main, wide radial-canals 

 which fork at their middle points, so that 12 

 canals, 30 apart, reach the circular vessel at 

 bell-margin. There are 24 long tentacles with 

 bulbous bases, each bearing a reddish-brown 

 ocellus. Numerous clubs and cirri on bell- 

 margin between the tentacles. 



The gonads are developed upon the edges 

 of the forked ends of radial-canals, there being 

 ia tu*, after Haeckel, 1879. a crescentic gonad upon the concave side of the 



crotch of each fork, and a pair of linear gonads upon the convex sides of the forks. There 

 are thus 3 gonads upon each main canal at its forking, 18 gonads in all. 



