SOME MEDUSA OF JAPANESE WATERS. 29 



The medusa measures 8 mm. in breadth, and 10 mm. in 

 height. 



Collected off Kunö in the Bay of Suruga, May 1900. 



Leptomedusse. 



Thaumantidae. 



Staurophora discoideaf n. sp. 



The umbrella is thin, disc-shaped, and fragile in consistence. 

 The velum is narrow. The stomach is cruciate with very long 

 limbs, each of which takes up about three-fourths of the umbrella- 

 radius. The oral opening is as long as the stomach, and is well 

 marked near the ends of the gastric cross by the much frilled 

 margin. The genital glands are minutely and longitudinally 

 folded. The number of these folds is about thirty on each side 

 of a limb of the gastric cross. The radial canals are short, simple 

 and slender. They are numerous, equal-sized, and grow much 

 crowded together. Many of them have one or two eye-spots on the 

 axial side of their somewhat thickened root. 



The medusa measures about 120 mm. in diameter, and oi-40 

 mm. in height. 



Found near Poromushiri in November 1904, and also at 

 Chippesaui in Saghalin. 



This species is very closely allied to St. mertensii Brandt, but 

 differs from it by the more numerous lateral folds of the genital 

 gland. In St. mertensii their number is stated by Brandt to be 

 seventeen. 



