AMPHOGONA. 125 



fig. 1). The four fertile radial canals are stout and easily traced ; but the 

 four sterile ones are, in all the specimens, less well defined, and, though 

 well preserved proximally, can hardly be traced at all as they approach 

 the ring canal. The constancy of this appearance suggests the possibility 

 that they may lack a well-developed lumen ; but this cannot be determined 

 except on better material than the present. 



Gonads. — These, four in number as stated, and located on four of the 

 radial canals, about two thirds of the length of the latter from the oral 

 pole, are sausage-shaped and attached to the canal by only a narrow stalk 

 (PI. 29, fig. 2). They are about 1 mm. in length, and are well developed in 

 all the specimens. The four sterile canals show no trace whatever of 

 gonads. 



Color. — This species exhibits a very characteristic and unusual pigmen- 

 tation, the entire manubrium being brilliant carmine, except for the margins 

 of the four lips, which are opaque white (PI. 29, fig. 1). The remainder of 

 the Medusa is colorless. 



This interesting form no doubt belongs to the intermediate fauna, since 

 it was never taken on the surface. 



Tetrorchis is evidently closely allied to Persa, from which it differs only 

 in having four instead of two gonads, and in the smaller number and 

 peculiar radial arrangement of the tentacles. It is true that Haeckel ('79, 

 taf. 16, fig. 12) figures a short gelatinous peduncle for P. lucema Haeckel, 

 but inasmuch as there appears to be no such structure in P. incolorata 

 (McCrady, '57, pi. 12, fig. 3), its presence or absence is not of much taxo- 

 nomic value in that genus. In the number of gonads (four) it agrees with 

 Stauraglaura, but the location of these organs near the distal ends of the 

 radial canals, instead of near the junction of the latter with the manubrium, 

 as well as the peculiar radial arrangement of the tentacles, seems to me 

 sufficiently important to indicate separate generic rank. The type species 

 is distinguished from all other Trachomedusae by these two features, as 

 well as by the absence of any gelatinous peduncle and by its characteristic 

 coloration. 



Amphogona Browne, 1904. 



Trachynemidae with peduncle; with numerous tentacles all alike; the 

 eight gonads spherical, pendant, home on subumbrella near distal end of 

 radial canals ; bell low and saucer-shaped. 



