452 



MEDUSA OF THE WORLD. 



secondary clefts of the stomach-pouches and there are about ioo sense-clubs. Moreover 14 

 of VanhofFen's specimens had 5, and only 4 had 4 tentacles and peronial strands. The ten- 

 tacles and stomach are pink or rose-red. Mouth a round opening. The marginal canal- 

 system is well developed. This medusa was most abundant at depths between 1,000 and 2,000 

 fathoms. 



Vanhoffen maintains that ALgina rosea is specifically distinct from AL. citrea, and certainly 

 his observations recorded above appear to give substantial support to his contention, but in 

 view of our imperfect knowledge of the development and range of variability of the species of 

 ALgina I prefer to suspend judgment upon the point. 



Fig. 300. — JEgina citrea, after Maas, in Hydromedusen Siboga Expedition. 

 jEgina rhodina Haeckel. 

 Plate 52, fig. 5; plate 54, figs. 11 — n.'" 



Mgha rhodina, Haeckel, 1879, Svst. der Medusen, p. 338, taf. 20, fign. 1 1-15.— Mayer, 1904, Mem. Nat. Sci. Brooklyn 

 Inst. Arts, and Sci., vol. 1, p. 27, plate 4, figs. 28, 29— Maas, 1905, Craspedoten Medusen der Siboga Expedition, 

 Monog. 10, p. 71. 



Mgina canariensis (young medusa?), Haeckel, Syst. der Medusen, p. 339. 



Solmundus tetralinus (young medusa?), Haeckel, 1879, Syst. der Medusen, p. 351, taf. 19, fig. 10. 



/Evina canariensis, Maas, 1893, Ergeb. der Plankton Exped., Bd. 2, K.c, p. 53. 



( >).£gina lactea, Vanhoffen, 1908, Narcomedusen der Valdivia Expedition, p. 50, taf. 1, fig. 3. 



Haeckel describes a mature medusa 40 to 50 mm. wide and two small "species," one 10 

 mm. wide, which he calls ALgina canariensis, and another 4 mm. wide, called Solmundus 

 tetralinus. They appear to be only stages in the growth of the same medusa, as will appear 

 from the tabulation of their characters, on the following page, as stated by Haeckel. 



These medusae were found by Haeckel in the Canary Islands. All have a simple, round 

 mouth-opening and the gelatinous substance of the bell projects downward in the form of a 

 wide cone into the stomach-space. Haeckel cut no sections and his statement that there is 

 no peripheral canal-system in "Solmundus tetralinus" requires confirmation for it is well 

 developed in AL. rhodina. 



I found a medusa at Mastic Point, Andros Island, Bahamas, which appears to be ALgina 

 rhodina. It is apparently intermediate between the ''tetralinus" and canariensis stages of 

 Haeckel. The bell was 7 mm. wide and there were 12 marginal sense-clubs, 3 upon each 

 interperonial quadrant. There were no ripe gonads. The stomach was intense green, but the 

 tentacles were pink. Green and red are often found interchangeably in the same species of 

 ALgina. Maas, 1893, records "ALgina canariensis" from off" the African coast in about lat. 

 12° N., south of the Cape Verde Islands. 



