706 MEDUSAE OF THE WORLD. 



of the stomach. On its inner side the ring-canal gives rise to an anastomosing network of 

 vessels which fuse with the perradial and interradial canals, but not with the adradial. On 

 its outer side the ring-canal gives off another network which fuses with all 16 radial-canals. 



4 main canals arise from the lower part of the stomach in the 4 principal radii. These 

 main canals fork and each fork extends down one of the 8 adradial mouth-arms, where they 

 branch many times and go to the numerous frilled mouths. 



The color of the medusa is usually blue, but occasionally dark-red. The mouth-frills 

 are brown and the mouth-arm appendages are milky-white, or nearly transparent. The 

 gonads are yellow, the male being lighter in color than the female. 



This medusa is abundant in the Inland Sea of Japan, and is also found off the coast of 

 China. 



It is the custom in Japan to preserve it with a mixture of alum and salt or between the 

 steamed leaves of a kind of oak. It is then soaked in water, flavored with condiments, and 

 when so prepared constitutes an agreeable food. 



Rhopilema rhopalophora Haeckel, from the Indian Ocean east of Madagascar, is closely 

 allied to, if not identical with, this Japanese medusa, but it is said to have a large, terminal 

 club at the end of each arm. This club is fusiform, triangular in cross-section, and as long 

 as the whole lower-arm itself. There are 144 lappets, the velar ones being rectangular, and 

 the bell is 100 mm. wide and hemispherical. In other respects it appears to be similar to 

 Kishinouye's medusa, although Haeckel's description is too brief to be satisfactory. 



Rhopilema hispidum Maas. 



( ?) Piltma clavigera, HAECKEL, 1880, Syst. der Medusen, p. 595. 



Rhizosloma hispidum, VANHOFFEN, 1888, Bibliotheca Zoologica, Bd. I, Heft. 3, pp. 32, 43, taf. 5, fign. I, 2. 



Rhopilema verrucosa, KISHINOUYE, 1899, Zoolog. Jahrbiicher, Bd. 12, p. 208, I fig. 



Rhopilema hhpidum, MAAS, 1903, Scyphomedusen der Siboga Expedition, Monog. n, p. 73, taf. 9, fign. 78-81. 



Bell hemispherical or higher than a hemisphere, and may become about 250 to 340 mm. 

 in diame'.er. Walls very thin; the exumbrella is thickly besprinkled with small, sharp-pointed, 

 conical projections. The 8 marginal sense-clubs have no ocelli, but above each is a large, 

 sensory pit with radiating furrows. 80 marginal lappets. The 8 sense-organs are each flanked 

 by a pair of very small, narrow, lanceolate lappets and there are typically 8 velar lappets in 

 each octant of the bell-margin; these velar lappets are oblong, rounded, and 3 times as long 

 and 5 limes as wide as the ocular lappets. 



The arm-disk is of the usual 8-sided form. The 4 interradial subgemtal ostia are, 

 according to Maas, not quite so wide as the perradial columns of the arm-disk between them; 

 but according to Kishmouye the subgemtal ostia in his "Rhopilema verrucosa," which appears 

 to be identical with R. hispidum, are 3 times as wide as the perradial columns. The 4 genital 

 cavities are only partially and irregularly fused and do not form a unitary genual space, as in 

 Mastigias and Crambessa, nor are they completely separated into 4 cavities, as in Cassiopea 

 (see Maas, 1903). The 8 mouth-arms are two-thirds as long as the diameter of the umbrella. 

 They are fused one with another in the upper thirds of their lengths and are free in their 

 lower two-thirds. There are 16 scapulets, 2 of which arise from the abaxial (outer) side of 

 each of the 8 upper arms. Each scapulet is simitar-shaped and forked at its outer end, and 

 is about half as long as the radius of the umbrella. There are frilled mouths and elongate 

 filiform appendages upon the upper side of each scapulet. 



The lower arms are 3-winged or Y-shaped in cross-section, one wing being inward and 

 axial, the other wings being lateral and directed outwardly. Each of these lateral wings 

 is of the shape of an equilateral triangle, and there are 4 elongate, sharp-pointed projections 

 from the abaxial angle of each wing. The pointed lowermost end of the lower arm terminates 

 in a large, club-shaped appendage, with a faceted, swollen end. This appendage is about 

 as long as the upper arm and there are other much swollen, club-shaped appendages which 

 arise between the frilled mouths of the 3 wings of each of the lower arms. 



The canal-system of the umbrella consists of 16 radial-canals, 4 perradial, 4 interradial, 

 and 8 adradial, the adradial ones being nearer to the perradial than to the interradial canals. 

 All of the canals extend quite to the bell-margin, and all give off side branches which form 

 an anastomosing network. A definite ring-canal is not present. The circular muscle-system 



