206 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Masbate Anchorage, Philippine Islands, on April 21, 1908, are as 

 follows : 



mm. mm. mm. 



Diameter of umbrella 174 1S9 128 



Diameter across zone of gonads 57 53 42 



Length of each mouth-arm 74 75 52 



Four other specimens (Cat. No. 27979, U.S.N.M.) were caught at 

 night upon the surface under the electric light at Jolo Anchorage, on 

 February 8, 1908; while seven more (Cat. No. 27924, U.S.N.M.) were 

 taken at Albatross station D 5230, between Bohol and Leyte, May 7, 

 1908. 



An abnormal but perfect specimen of Aurellia aurita was found 

 at Tortugas, Florida, on July 27, 1914. This aberration closely re- 

 sembled the normal A. labiata of the Pacific. There were 16 deep 

 notches in the bell-margin, 8 perradial and 8 interradial, and the 

 velumlike marginal membrane was like that of A. labiata. The 

 small subgenital ostia and simple mouth-arms also recalled A. labi- 

 ata; but the terminal branches of the adradial-canal system did not 

 anastomose and in this resembled A. aurita rather than A. labiata. 

 The case is interesting, as it leads one to suspect that A. labiata of 

 the Pacific has been derived as a mutation from the universally dis- 

 tributed A. aurita. The bell of this Tortugas medusa was 270 mm. 

 in diameter; diameter of genital cross, 78 mm. Palps simple and 

 each about one-eighth longer than the bell-radius. Eight sense 

 organs, 8 interradial notches in the bell-margin. Eight straight, sim- 

 ple, non-pigmented perradial-canals, 8 straight pink-colored inter- 

 radial-canals. The sparingly branched adradial-canals reach the 

 bell-margin without anastomosing, and in this respect resemble those 

 of A. aurita. The male gonads were pink, the tentacles rich purple, 

 the velarium creamy white, the palps purple-pink, and the gelatinous 

 substance pink. 



Order RHIZOSTOMAE. 



Scyphomedusae without marginal tentacles and with numerous 

 mouths borne upon four dichotonously branched (eight) mouth-arms. 

 Most of these forms are tropical and none are found in Arctic seas. 

 They are the conspicuous large jellyfishes of harbors and coastal 

 waters in the East Indies, although usually rare and represented by 

 but few species in the West Indies. 



Genus CASSIOPEA Peron and Lesueur, 1809. 



Cassiopea Peron and Lesueur, 1S09, Annal. du Mus. Hist. Nat. Paris, vol. 

 14, genre 24, p. 356.— Mayer, 1910, Medusae of the World, vol. 3, p. 636. 



Generic Characters. — Rhizostomata pinnata with eight (four pairs 

 of) adradial, complexly branched mouth-arms, the lower or ventral 



