688 



MEDUSAE OF THE WORLD. 



their outer ends. The mouth-arms are strongly compressed laterally, being only 3 mm. in cir- 

 cumferential and ii mm. in radial width at their points ot origin from the mouth-arm disk. 

 A single duct extends into each mouth-arm, but this soon sends off a pair of side branches to 

 the lateral wings, and a pair of secondary branches arises from these and extends down the 

 main shaft of the mouth-arm (fig. 416, c). 



There are 8 wide rhopalar canals of which the 4 perradial ones arise directly from the 

 stomach, but the 4 mterradial arise from the confluence of a pair of forks. 7 to 9 narrow 

 vessels arise from each inter-rhopalar octant of the stomach and extend outward toward the 

 bell-margin, giving oft numerous, anastomosing side branches which form a network connect- 

 ing all the canals. There is no definite ring-canal. 



Near the hell-margin there is a sharp, angular bend in the subumbrella surface so that 

 the outer annulus of rhe subumbrella extends downward vertically and at right angles with 

 the inner zone ot the subumbrella. There is a wide annulus of circular muscles in the sub- 

 umbrella. These muscle-fibers are unbroken hut somewhat thinned in the 8 rhopalar radii, 

 and the muscular-zone is wider in the interradn than in the perradn, but does not extend to 

 the edges of the arm-disk. 



In formalin the rhopalar radial-canals and the proximal parts of all other canals adjacent 

 to the stomach are bluish-purple. The mouth frills are brownish to brownish-purple. The 

 bell is milky and the muscles and gonads dull brownish-yellow. 



A single perfect specimen was obtained by the U. S. Fisheries Bureau steamer Albatross 

 on April 8, 1908, along the shore at Mantocao Island, west coast of Bohol, Philippine Islands. 



FIG. 417. Lobonema smithii. Drawn by the author, from a preserved specimen. 

 View of subumbrella. Muscular system shown on right and vascular system on left. 



Genus LOBONEMA, gen. nov. 



The type species and only known form is Lobonema smithii from Manila Bay, Philippine 

 Islands. 



GENERIC CHARACTERS. 



Rhizostomata triptera in which the marginal lappets are greatly extended, tapering to 

 pointed ends. Mouth-arms with numerous filaments. Mouth-arm membranes perforated 

 by window-like openings. 8 rhopalia, 16 radial-canals, and a ring-canal which gives off 

 anastomosing vessels on both its inner and outer sides. The inner network does not connect 



