18,1 Light: Philippine Scyphomedusan Jellyfishes 35 
The 8 rhopalia are small but distinct and have a porcelain- 
white color in life. There is a very small exumbrellar sensory 
pit and a distinct subumbrellar shelf. (See fig. 1.) 
The marginal lappets are very thin and fragile and quite 
transparent, the canal system not extending into them. There 
are 6 velar lappets in each octant, the 2 lying next the ocular 
lappets being smaller than the other 4. The lappets present 
only a slight convexity and in large specimens are hardly to be 
made out distally. They are separated on the exumbrellar sur- 
face, however, by distinct, broad and deep grooves which are 
marked by the absence of the warts and the brown color of the 
remainder of the exumbrella. In the largest specimen there 
appear, in the center of many of these grooves, small rudi- 
mentary lappets marked by a slight distal projection and a very 
small area of brown color. 
The mouth-arm disk which is 4-sided has a width of 45 milli- 
meters in the figured specimen. Each mouth-arm pillar (two 
united mouth arms) has a diameter of 20 millimeters where it 
joins the mouth-arm disk, and a minimum diameter of 10. milli- 
meters between the subgenital ostia which have a width of about 
30 millimeters, or 3 times that of the pillars which separate them. 
The subgenital porticus is unitary. 
The mouth arms, which in the figured specimen are about 
70 millimeters long, exclusive of the terminal clubs, are very 
narrow externally and flat in the radial plane, the fleshy, un- 
branched portion being 20 millimeters broad and only 7 milli- 
meters thick. The outer surface is bare for about 50 millimeters 
after which the arm is dichotomously branched once and each 
branch twice dichotomously divided again. The inner surface 
of each branch and of each arm is also alternately branched. 
The mouths surrounded by tiny tentacles are scattered rather 
sparsely on the inner and lower surfaces of the minor branches. 
Scattered between the mouths and most numerous near the cen- 
ter of the disk are very small, slender, delicate filaments, and 
projecting from the tip of each arm, giving it an appearance quite 
different from more typical Rhizostomata dichotoma, is a term- 
inal club having a length of about 35 millimeters. This club, 
which has a surface color of light diffuse brown, is covered with 
low nematocyst-bearing warts and contains a continuation of 
the main canal of the arm at least half the diameter of the club 
and showing, like all the canals of the mouth arms, the clear 
purple color which gives this medusa a most beautiful and dis- 
tinctive appearance. 
