1903] Report on some Medusae from Norway and Spitzbergen. 19 



Aequorea norvegica, nova species. 

 Plate V, fig. 1—5. 



Description. 



Umbrella very thin, much broader than high. The base of 

 the stomach is flat, (its diameter about half that of the umbrella) 

 and not very long. The mouth has 46 lips, which are long (9 — 10 

 mm.) and have fimbriated edges. Radial canals numerous (98). The 

 gonads, on all the radial canals, are band-shaped, bilaminate, and 

 extend from near the stomach to within a short distance of the 

 ring canal. Tentacles about 200 in number, closely packed together 

 on the margin; their basal bulbs are long and tapering, laterally 

 compressed. Between them there is generally a small bulb, either 

 without a tentacle, or with a very minute one. Marginal sense 

 organs very numerous, probably one, perhaps two, between eveiy 

 tentacle and bulb. 



(Transparent. Gonads white or grey. 0. Nordgaakd.) 



Size. Umbrella about 90 mm. in diameter. 



Moskenstrommen, Lofoten Isles: within the Arctic Circle. 



Tåken at the surface. 1. 3. 1899. One specimen. 



I have failed to identify this medusa with any that have been 

 previously described, and with some hesitation announce it as a new 

 species. 



Nearly all the descriptions by the earlier writers lack the de- 

 tails which are now essential for distinguishing one species from 

 another, and it is practically impossible to identify many of the 

 species with any degree of certainty. Too much importance has 

 been attached to the number of radial canals and tentacles, which 

 show a great numerical variation quite independent of the natural 

 increase in number due to development. The exact shape of sto- 

 mach and whether the mouth is open or closed are scarcely suitable 

 for generic characters. The fact that an Aequorid is occasionally 

 caught with its mouth wide open is no evidence that it is perma- 

 nently kept open. This condition is easily produced when a living 

 specimen is given its first dose of Formalin, as I have myself wit- 

 nessed. 



The old genus Aequorea has been gradually split up into seve- 

 ral genera and how many these are valid can only be decided when 

 more is known about the life-histories of the numerous species. 

 The whole family certainly requires a revision, but it is useless to 



