HETEROTIARA ANONYMA. 217 



twelve (PI. 41, fig. IS), four radial and eight adradial. In the "Siboga" 

 specimen Maas (: 05) records eight tentacles, four radial and four interradial • 

 but as he had only a single specimen it is by no means safe to assume that 

 eight was the final number. On the contrary, in view of the variation in 

 number in the two specimens in the present collection it is probable that 

 with further growth more tentacles would have been formed. The tentacles 

 are long (not broken off as Maas found them), hollow, and flexible. There 

 are no distinct basal bulbs. 



As in Sibogita, the gelatinous substance of the bell margin extends out- 

 ward and partially encloses the tentacle bases ; a similar condition is de- 

 scribed and figured by Maas (: 05^) for Heterotiara. Maas has mentioned 

 endodermic pigment at the bases of the tentacles ; but none was to be dis- 

 tinguished in the " Albatross " specimens, perhaps on account of their con- 

 dition or preservation. 



Alaniihrium. — The manubrium, as noted by Maas, is very different from 

 that of Tiara and more nearly resembles the condition in the Leptomedusae. 

 In both specimens it is barrel-shaped ; in one hanging to the bell opening, in 

 the other contracted ; it is seated directly on the subumbrella surface, with- 

 out peduncle. The mouth is quadrate and surrounded by simple lips. 



The vascular system consists of four broad unbranched radial canals, 

 and of the ring canal. In one specimen there appears to be a rudimentary 

 triangular centripetal canal, such as is described by Maas (: 05, p. 19, taf. 3, 

 fig. 20), opposite one of the adradial tentacles; but the condition of the 

 margin is such that it is impossible to make certain whether this structure 

 is really a canal or not. 



Gonads. — The permanently interradial location of the gonads is one 

 of the strongest reasons for classing this genus in the Bythotiaridae in 

 spite of the simplicity of the canal system. They are entirely discontinu- 

 ous in the perradii and limited entirely to the manubrium. They have no 

 definite transverse folds, such as are characteristic of Sibogita. Both 

 specimens are females, with ova so large that they are visible even to the 

 unassisted eye. 



Color. — In both specimens the gonads were opaque yellowish ; other- 

 wise they were colorless. 



The main differences between the "Albatross" and the "Siboga" speci- 

 mens, apart from the more advanced condition of the gonads in the former, 

 are that the former have eleven or twelve tentacles, the latter only eight, 



