LKPTOMKDUS.E — .EQUOREA. 



331 



iEquorea albida A. Agassiz. 



Plate 43, figs. 1-5; plate 44, fig. 5. 



/Enuona albida, Agassiz, A., 1862, in L. Agassiz's Com. Nat. Hist. U. S., vol. 4, p. 359; 1865, North Amer. Acal., p. no, figs. 

 160-162.— Haeckel, 1879, Syst. der Medusen, p. 221 .— Verrill, 1873, Report Com. Fish and Fisheries U. S., for 1871-72, 

 p. 729. 



This medusa is, I believe, only a well-marked northern variety of JEquorea forskalea, 

 but it may be distinguished by its color, the entodermal lamella of the bell being a decided 

 green and the tentacle-bulbs often orange with black-colored granules. Such colors are not 

 recorded in JEquorea forskalea. 



Bell about 60 mm. wide, somewhat miter-shaped, with flaring sides, slightly higher than 

 a hemisphere. About 300 slender tentacles, longer than bell-diameter and with well-developed 

 basal bulbs which contain excretion papillae. The lithocysts are about twice as numerous as 

 the tentacles and each lithocyst contains 2 to 4 spherical concretions. Velum is well devel- 

 oped. There are 80 to 100 simple, straight radial-canals and a narrow, circular tube. Stomach 

 is wide and shallow, its diameter being about one-third that of the bell. The throat-tube 

 is short and conical and the mouth-opening is surrounded by small lappets which are as 

 numerous as the tentacles. The gonads are linear and are developed upon nearly the entire 

 lengths of the radial-canals, leaving both ends free. The gelatinous substance of the bell 

 exhibits a slight bluish tinge. The entodermal lamella is of a decided green. The entoderm 

 of the stomach, gonads, and tentacle-bulbs is milky or cream-colored. In some individuals 

 the entoderm of the tentacle-bulbs is of a decided orange and contains black granules. (See 



fig. 189.) 



Young medusa (plate 43, fig. 1). — The youngest medusa observed was 0.75 mm. in 

 diameter. There were only 4 tentacles. 2 of these were quite long and possessed well-developed 



Fit;. 190. — .Squorea tenuis, by the author, from a medusa from Woods Hole, 

 Massachusetts, Sept., 1907. 



basal bulbs, and the other 2 were rudimentary. There were 8 lithocysts, each containing a 

 single concretion. These were situated upon the bell-margin, very near to the bases of the 

 tentacles. The velum was large. There were 4 radial-canals and the manubrium was a 

 simple tube with 4 cruciform lips. 



As development proceeds the tentacles increase in number, and closely following them 

 the radial tubes grow downward from the margin of the stomach to the circular canal. The 

 lips increase in number much more slowly than do the radial-canals. The gonads and excretion 

 papilla; do not make their appearance until after the medusa has acquired 16 radial-canals. 

 A. Agassiz succeeded in rearing the egg of this species and it developed into a small hydroid 

 1.25 mm. in height and provided with 12 long, straight tentacles. 



This form is common along the New England coast of the United States from June 

 until October. It has not been taken either at Beaufort, North Carolina, nor at Charleston, 

 South Carolina, and is probably confined to northern waters. 



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