J. W. Fewkes — Deep-Sea Medusae. 173 



penetrates. We may have here, what we so often find in deep- 

 sea animals, a reduction in the size and efficiency of the special 

 organ of sense to fit the medusa for the conditions under 

 which it must live in great depths. Stated in a startling way, 

 we might speak of Atolla as a blind medusa. This statement 

 would hardly be justifiable and we can at present go no further 

 than to say that the special sense-bodies of sight * are supposed 

 to be rudimentary. It must however be borne in mind that no- 

 where among Acraspeda do we have so many, twenty-two, 

 sense-bodies as here. In some specimens there are twenty-eight 

 sense- bodies in this genus. 



It is extraordinary that one of the known species of Atolla, 

 {A. Wyvillii Haeck.), comes from the Antarctic Ocean, while 

 our two species were both from the warm (?) water of the Gulf 

 Stream. In the southern hemisphere its lowest limit is about 

 2000 fathoms, while north of the equator it comes from the 

 surface or within a few hundred fathoms. 



Among the medusae collected by Lieut. Greely in the icy 

 waters of Lady Franklin Bay, is an interesting jelly-fish allied 

 to Atolla. This genus {Nauphanta) has been found but once 

 before and then by the naturalists of the Challenger in the neigh- 

 borhood of the island of Tristan d'Acunha in the South Atlantic. 

 In the latter locality it is recorded from about 1500 fathoms, 

 while in Lady Franklin Bay it is found on the surface. From 

 several differences in these two specimens, those from the Arctic 

 and those from the South Atlantic, I have supposed the boreal 

 form to be new and have called it by the specific name polaris.f 

 The Challenger specimens were placed under a new genus 

 called by Hseckel, Nauphanta.% 



Before we consider the relationship between Atolla, Nau- 

 phanta and other related medusas, ascribed to the deep-sea, let 

 me mention another new medusa collected by the Albatross in 

 the Gulf Stream. The genus JVauphantopsis, is of interesting 

 affinities, since it has the same central disk as Nauphanta and 



* Whether the " eye " of the jelly-fish can distinguish form or not has not been 

 demonstrated. Simple experiments made by passing rays of light through dishes 

 in which they are confined, or the simple fact that they almost always congregate 

 on the illuminated side of the same, are not conclusive to me that they distinguish 

 form. Experiments with sensitive plates to show the depths to which light pene- 

 trates the water are most suggestive in this connection. It seems pertinent to the 

 whole inquiry to ask whether looked at from the physical side there are not rays 

 of light of such a nature that the vertebrate eye is not able to perceive them, but 

 which may act upon the visual organs of other animals. 



f Nauphanta polaris has a central disk as in Atolla, a coronal fossa, and a 

 corona, which, however, is formed of sixteen socles, eight of which bear tentacles, 

 tentacular socles, and eight sense-bodies. The outlines of these socles is more 

 clearly marked than in Atolla on the upper surface of the corona, which they 

 form, on account of the deep sculpture which separates them. 



\ The name Nauphanta was preoccupied in 1879, when applied to this Medusa, 

 having been given to a worm in 1 864. 



