NARCOMEDUS^E — .ffiGINA. 



453 



Growth-stages in the Development of JEgina rhodina. 



Size of bell in mm. 



Shape and size of the 

 8 stomach-pouches. 



Length of 4 tentacles 

 in terms of bell- 

 radius (r) 



Number of marginal 

 sense-clubs. 



Color. 



Gonads. 



"Solmundus 

 tetralinus" Haeckel. 



4 high, 4 wide. 



Small, quadratic, with 

 rounded edges. 



"Aegina canadensis' 

 Haeckel. 



? (Not seen.) 



4 high, 10 wide. 



Twice as wide as long, 

 with rounded edges, 

 extending to near the 

 bell-margin. 



4 r 



16 



Stomach, gonads, and 

 tentacles rose-red. 



Present. 



JEgina rhodina 

 Haeckel. 



20 to 30 high, 40 to 50 

 wide. 



Quadratic, separated by 

 small intervals. Not 

 half as long as distance 

 between periphery of 

 central stomach and 

 bell-margin. 



2 r 



16 



Stomach light-red. Go- 

 nads and tentacles 

 rose-red . 



Present. 



JEgina rhodina is probably widely distributed over the tropical Atlantic, but appears to 

 be rarer off the American coast than it is off the coast of Africa. It is, however, abundant at 

 times in the Gulf Stream off the Florida coast. 



Further details of the mature medusa are given in the table, showing a synopsis of the 

 species of JEgina on page 450. 



Vanhoffen, 1908, Narcomedusen der Valdivia Expedition, p. 50, tat. I, ng. 3, records 

 the capture of a medusa which he calls JEgina lactea in the South Atlantic off the African 

 coast between the mouth of the Congo and Great Fish Bay from a depth of 350 to 500 fathoms. 

 It has 4 tentacles, 8 simple, gastric pouches, and 10 sensory-clubs per quadrant. The bell is 

 1 1 mm wide and 8 high. The only distinctive features, however, are the white, milky-colored 

 stomach-pouches and flesh-colored tentacles; but the coloration of species of JEgina seems 

 to be highly variable, and I can not be sure that this medusa is not merely a variety of JEgina 

 rhodina. I believe, indeed, that future studies will probably show that the Atlantic JE. rhodina 

 is specifically identical with the Pacific JE. citrea. 



jEgina eschscholtzii Haeckel. 

 JEgina eschscholtzii, Haeckel, 1S79, Syst. der Medusen, p. 339. 



Bell 20 mm. wide, 20 mm. high, rounded. 4 tentacles not quite as long as bell-radius. 

 Marginal sensory-clubs ( ? ) Stomach with a wide, conical, gelatinous plug, extending down- 

 ward into its cavity, as in JE. rhodina. Mouth at end of a conical neck and provided with 4 

 large triangular lips. 8 quadratic genital pouches, somewhat longer than wide. Found at the 

 Azores Atlantic Ocean. One specimen out of the 4 found had 5 lips, 5 tentacles, and 10 

 genital'sacs. This species is distinguished solely by its having 4 or 5 lips instead of a circular 



mouth-opening. 



jEgina brunnea Vanhoffen. 



JEgina brunnea, Vanhoffen, 1908, Narcomedusen der Valdivia Expedition, p. 51, taf. I, fig. 4. 



This medusa resembles M. rhodina but the stomach-pouches are mottled with brown 

 and the tentacles and peronia are white. A single specimen 10 mm. wide was found in the 

 Indian Ocean from a depth of 1,000 fathoms, in the North Equatorial Stream. 



jEgina alternans Bigelow. 



Mgina ahernans, B.gelow, H. B., .909, Mem. Museum Comp. Zool. at Harvard College, vol. 37, p. 74. pla«= 17, ng. 1. 



Bell 40 mm. wide, high, rounded. Exumbrella smooth. 4 tentacles as long as bell- 

 diameter At least 2 sensory-clubs per quadrant. There are only 4 interradial marginal 

 stomach-pouches without any trace of interradial notches, but the radial notches adjacent to 

 the peronia are very deep. Thus we find in this medusa only 4 simple stomach-pouches alter- 



