70 THE MEDUSAE. 



explained as the result of the individual variation which, as I have shown, 

 occurs in the number of tentacles, or of different stages in growth. Since 

 furthermore, the two were recoi-ded from the same general region of the 

 South Atlantic, it is altogether probable that they are in reality identical 

 and show no important characters distinctive from the present series ; 

 but until the question of the identity of S. faberi with S. incisa can re- 

 ceive a final answer based on a fresh study of South Atlantic specimens, I 

 have thought it best to use the latter name for the present species. In 

 the meantime it may not be amiss to point out that Solmissus incisa will 

 probably be found, like Rhopalonema velatvm, Aglaura hemistoma, Nausithoe 

 punctata, Periphylla hyacinthina, and so many other oceanic Medusae, to be of 

 practically universal distribution in the warmer portions of all oceans. 



To make any final statement of the bathymetric range of this species 

 would be premature. The only specimens taken at the surface are the two 

 very small ones ; all the large specimens, nine in number, from eight different 

 stations, come from between three hundred (four hundred in one case) fath- 

 oms and the surface. It is probable, then, that this will prove, at least 

 when adult, to be an intermediate, not a surface form. 



Aeginidae Gegenbaur, 1856. 

 sens. em. Maas ( : 04% : 04 c ). 



Narcomedusae with a precise number of antimeres and with gastric 

 pockets adradial, usually twice as numerous as the tentacles. 



Peripheral canals may (Aegina) or may not (Solmundella) be present; so 

 far as known, no member of the family has otoporpae. 



It is in this family that the recent classification of Maas shows the greatest 

 divergence from the earlier system of Haeckel ('79), and the greatest improve- 

 ment over it. Unlike the Cunanthidae, the genera of Aeginidae have precise, 

 determinate numbers of tentacles ; and in this family this character is a very 

 constant and reliable one. It is used by Maas (: 04% : 04°), and I believe rea- 

 ilily, as the chief generic distinction in the family. The number of gastric 

 pockets is less reliable ; for while in the adult they are always at least twice 

 M numerous as the tentacles, in some instances, as in Aegina, they are known 

 to undergo -till further subdivision, so that they become four times as numer- 

 ous as the tentacles. 



