MEDUSAE. I. 



47 



If we compare the statements of the literature with the experiences derived from the material 

 dealt with in the present paper, we will get the following general picture of the distribution and oc- 

 currence of Staurophora mertensii: In the Atlantic as well as in the Pacific the main distribution of 

 the species is within the arctic region; in both of these oceans, however, the species may penetrate 

 fairly far southwards into boreal regions, though decreasing in frequency. It is exceedingly numerous 

 off the northern and eastern coasts of Iceland, but somewhat scarce off the southern coast, which is 

 washed by the water of the Gulf Stream. In the Barents Sea it mainly keeps itself in the northern 

 and eastern cold parts, whereas it only penetrates to the south-western part, near the Murman coast, 

 in the autumn or in very cold summers. It does not seem to be scarce in the fjords of Finmarken, 

 but only at a few occasions has it been met with at more southerly parts of the Norwegian coast 

 The occurrence of quite young specimens at Heligoland demonstrates that the species may live and 

 breed in the North Sea, but it is apparently very rare in that area. Off the Atlantic coast of North 

 America it is indigenous in the Gulf of Maine, but south of Cape Cod it is only met with occasion- 

 ally and only in the spring months. In the eastern part of the Pacific its occurrence is limited to 

 the coast of Alaska, in the western part it penetrates as far southwards as extends the influence of 

 the cold Kamtschatka Current 



Everywhere the species is a well-marked coastal-water form. Particularly it is worth mention- 

 ing that all finds of young individuals, hitherto known, have been made very near the shore. Young 

 specimens are always found in the spring, April May, whereas the grown-up specimens are mainly 

 found in August or later (cfr. the statements of the occurrence in the Barents Sea). There can be no 

 doubt, but that Stauropkora has a neritic, fixed hydroid-generation, which hibernates, and from which 

 the young medusae are deliberated in the spring. 



Of great interest is the bipolar distribution. The mediisa described by Browne from the 

 Falkland Islands was found at the beginning of January; thus also in the Antarctic the species is a 

 summer-form. 



Family Thaumantiadae. 

 Genus Melicertum L. Agassiz. 



This genus has an interesting but not very joyous history, in so far as it has given rise to 

 much confusion owing to a peculiar want of criticism by some otherwise prominent authors. Haeckel 

 (1879), as tne fi rst i has called attention to this confusion and unravelled the history of the genus. But 

 at the same time Haeckel introduced the generic name Melicertidium for a species, which was later 

 found to belong to the same genus, which L. Agassiz called Melicertum, and thus the question rose, 

 which of these two names ought to be used as the correct one. Browne (1905) and Mayer (1910) 

 have discussed this question and thereby given new accounts of the history of the genus. As the said 

 authors arrive to opposite results with regard to the question of the correct name, I have thought it 

 worth while to deal with the matter once more from a historical point of view, in order to make out 

 my position to that question. 



The Medusa campanula, as described by Fabricius (Fauna groenlandica, 1780, p. 366), had 



