Boone, Coelenterata, Cruises of "Ara" and "Alva" 51 



ostia are each about twice as wide as the columns between and are 

 constricted medially. The subgenital porticus is unitary. 



There are eight mouth-arms, each of which is about as long in 

 the dead specimen as the bell radius. The simple upper part is 

 about 0.4 as long as the frilled distal portion which is three- 

 winged. The frilled mouths are numerous along the margins of 

 the three wings and also for considerable distance inward along 

 the sides of each wing. Numerous small, club-shaped vesicles 

 arise between the mouths on the outer sides of the mouth arms ; a 

 few long filaments similarly arise on the ventral or inner sides of 

 the mouth-arms. The distal end of each mouth-arm terminates 

 in a clavate tentacle or filament, which varies in length from zero 

 to approximately equal to the bell diameter. This club is subtri- 

 angulate in cross-section and contains an axial canal. Each mouth- 

 arm contains a main canal that arises from the stomach and 

 within the arm dividends into three branches which extend to the 

 three series of frilled mouths of the winged lower part of the arm 

 with ramifications and distally these three unite in confluence with 

 the axial canal of the distal club. 



The central stomach is cruciform and gives rise to the eight 

 radial canals which extend to the rhopalia. These radial canals 

 are communicant by means of the wide ring canal which is situ- 

 ated well inward from the margin. Eact octant of the stomach 

 between the rhopalar canals gives rise to six to nine anastomosing 

 radial canals that fuse with the ring canal. The ring canal gives 

 rise on the outer side to a fine mesh network of anastomosing ves- 

 sels that extend into the marginal lappets and unite with the ends 

 of the rhopalar canals. The circular muscle area of the marginal 

 zone of the exumbrella is very much interrupted in the eight rho- 

 palar radii. The gonads consist of four folded walls forming cru- 

 ciform sides of the subgenital aperture. 



This species is a rapid swimmer, moving by an incessant rhyth- 

 matic pulsation of the bell rim which alternately contracts and 

 expands. 



The young stage of this species was described by Agassiz and 

 Mayer (1899). 



References : Cephea papua, Lesson, R. P., in DuPerry, L. I., 

 Voy. Autour du Monde, La Coquille, 1822-25, Zool., t. II, pt. 

 II, 1829, p. 122, pi. 11, figs. 2, 3. 



