I'O- B.] INTRODUCTION. 



a small, perfectly hyaline Copepod of a still more peculiar appearance, and 

 at once recognizable as a species of the highly remarkable genus Mormonilla 

 of Giesbrecht, the systematic position of which is still rather doubtful. Only 

 two species of this genus have hitherto been recorded, and both of them were 

 found in the tropical part of the Pacific, south of the equator. The polar 

 form so closely resembles one of the two species described by Dr. Giesbrecht, 

 that I should have been much inclined to identify the two forms, were it not 

 that the great distance between the occurrences seems to forbid such an 

 identification. The very close, and apparently genetic relationship between the 

 two polar species of the amphipodous genus Pseudalibrotus to be described 

 below, and those occurring in the Caspian Sea, is another remarkable instance, 

 which seems fully to corroborate the correctness of the assumption of geologists 

 as to a direct connexion in olden times between this isolated basin and the 

 North Polar Sea. 



In order to show the general character of the pelagic fauna in the Polar 

 Sea, I subjoin lists of the species found in 5 widely-separated tracts of the 

 region traversed by the "Fram". 



No. 1. 



12th to 24th October, 1893. 



Sea north of New Siberia (beginning of the drift). 



In about 78^ N. Lat, 136° E. Long. 



Sabinea septemcarinata (Sab.). Myto-stage. 



Parathemisto oblivia Kroyer. 



Metopa longicornis Boeck. 



Gammarus locusta, var. mutata, Lilljeb. 



Calanus finmarchicus, Gun. 



— hyperboreus, Kroyer. 

 Pseudocalanus elongatus, Boeck. 



— major, G. 0. Sars. 



— pygmceus, G. 0. Sars. 

 Euchceta norvegica, Boeck. 



