SIBOGITA SIMULANS. 213 



the absence of tentacular bulbs, that there is good reason to believe that the 

 three genera form a natural association. Furthermore it may be pointed 

 out that it is unwise to lay much weight on the supposed branching of the 

 canals in Bythotiara, since there is a possibility of the same explanation 

 there as in Sibogita. Bythotiara, like Sibogita, was founded for a single 

 specimen, and, so far as I am aware, has not been recorded since. Dicho- 

 tomia Brooks and Netocertoides Mayer (: 00 b ) probably belong to this family, 

 altbough in the former the structure of the gonads more nearly resembles 

 that in AmpMnema larrida and A. odaedra. 



The closest relationship of the Bathytiaridae is undoubtedly with the 

 Tiaridae : but they are easily distinguished from that family by the greater 

 development of the manubrium, which, as in most Leptomedusae, is dis- 

 tinguishable into basal, gastric, and oral regions; by the structure of the 

 gonads, which are permanently interradial instead of having this primitive 

 location masked with growth as is the case in most Tiaridae ; by the struc- 

 ture of the bell margin ; and by the fact that the tentacles have no distinct 

 bulbs or ocelli. 



Sibogita Maas, 1905. 

 sens. ein. 



Bythotiaridae with four primary radial canals, and, in addition, with 

 twelve (or more) centripetal canals, which secondarily come to join the 

 cruciform base of the stomach; gonads transversely folded; bell laterally 

 flattened. 



Although the specimens are undoubtedly congeneric with Sibogita, I 

 question their specific identity with S. geometrica Maas, since the chief 

 difference between the two, order of development of canals and tentacles, is 

 probably not to be explained as caused by differences in growth. It is 

 unfortunate that the series of this genus so far examined bave been so 

 small ; and for that reason final decision is still uncertain ; but on the 

 whole it seems best to institute a new species for the three " Albatross " 

 specimens. 



Sibogita simulans, sp. nov. 



Plate 5, figs. 4, 6, Type ; Plate 41, figs. 8, 0; Plate 43, figs. 1, 2. 



Station 4635 ; surface ; 2 specimens. 



Also one specimen, from the United States National Museum, collected 



