SOME MEDUSA OF JAPANESE WATERS. 19 



The species grows to a size of about 360 mm. in diameter. 

 Found on the coasts of Saghalin from May to August. 



Ulmaridae. 

 Paruinhrosa, u. g. 



Uhnaridse with eight sensory clubs, twenty- four tentacles, and 

 sixty-four marginal lobes, every two of which alternate with a 

 sensory club or a tentacle. 



JParumbrosa ±)olylohata , n. sp. 



(PI. IV, Figs. 20-23.) 



The umbrella is flat, disc-shaped, about four times as broad 

 as high. Its gelatinous substance is very rich in water and con- 

 sequently of a very delicate consistence. The exumbrella is finely 

 and uniformly granulated. The umbrella margin is divided into 

 sixty-four lobes : six lanceolate velar lobes between every two 

 narrow, divergent, ocular lobes. 



The tentacles number twenty-four. They are laterally com- 

 pressed, and are rich in muscular fibres on the axial side. 

 Nematocysts are mostly found on the abaxial side of the tentacle 

 in transverse bands. The adradial tentacles are better developed 

 than the others. 



The subumbrella is nearly smooth, the development of the 

 muscular system being very weak. 



The central stomach cavity is nearly round and flat, with 

 four interradial pits on its floor. These pits bulge out as conical 

 processes into the subgenital cavities. They may be compared to 



