INTRODUCTION 205 



sub-Antarctic region are viviparous, a perfectly astonishingly high percentage in com- 

 parison with other regions, where only very few species are viviparous. Foremost comes 

 here the New Zealand region with six viviparous species out of a total number of forty- 

 one species, thus ca. 15 per cent, all other regions having a still smaller number of 

 viviparous forms. Particularly the difference between the Arctic-sub-Arctic and the 

 Antarctic-sub-Antarctic region in regard to the number of viviparous forms is very 

 striking ; but this has been repeatedly emphasized, so I shall not go into details here. 



I may here mention a statement in literature which would seem to show that the 

 Korean seas are remarkably rich in viviparous Ophiurids. Duncan in his paper On some 

 Ophiuroidea from the Korean Seas (Journ. Linn. Soc. ZooL, xiv, 1878, p. 464) says 

 about Ophionereis dubia, var. sinensis, Dune, that "it has a marsupium, and doubtless, 

 as was commonly the case in these Korean seas, it was viviparous". During a visit 

 to the British Museum in July 1935 I took the opportunity of re-examining all these 

 supposed viviparous Ophiurids from the Korean seas and was able to ascertain that — 

 as I expected — it is all a mistake. The Ophionereis happened to be preserved (dried) in 

 such a contracted state that one of its bursae is widely open, looking indeed like a kind 

 of marsupium. But it is only an empty bursa, and there is not the slightest sign that this 

 or any other of Duncan's Ophiurids is viviparous. At the time Duncan wrote this paper 

 the anatomy of the Ophiurids was still very imperfectly known. Not until Ludwig, in 

 this same year, 1878, published his famous paper Beitrdge zur Anatomic der Ophiuren 

 (Zeitschr. wiss. Zool., xxxi) did we get a real understanding of the bursae of Ophiurids 

 and their relation to the gonads. It was thus quite natural for Duncan to take the widely 

 open bursa of his Ophionereis for a marsupium ; and seeing the bursal slits also in his 

 other Ophiurids, he naturally concluded that they all were viviparous. But he did not 

 open any of them to ascertain whether there were really young ones within these sup- 

 posed " marsupia ", and did not think either of looking at other Ophiurids, or he would 

 have concluded that they were all brood-protecting, or else have discovered his mistake. 

 Thus we need no longer concern ourselves with these mysterious viviparous Ophiurids 

 of the Korean seas. 



In my paper Biological observatio7is on Ophiurids (Papers from Dr Mortensen's 

 Pacific Exped., Lxiii, Vid. Medd. Dansk Naturh. Foren., 93, 1933) I gave a revised 

 list of all known viviparous Ophiurids, amounting to thirty-two. As Amphipholis 

 patagonica, and also A. japonica and sobrina, are there reckoned as distinct species, 

 whereas in reality they are probably all indistinguishable from A. sqiiarnata, the actual 

 number of viviparous Ophiurids known up to 1933 was only twenty-nine species. The 

 discovery of no less than twenty-five new viviparous Ophiurids, as stated in the present 

 report, makes it desirable to revise the whole matter again, particularly with regard to 

 the question of the hermaphroditism of the viviparous Ophiurids. 



The Ophiurids till now known to be viviparous are: 



1. Astrochlamys bruneus, Koehler. Sexes separate. 



2. Ophiomyxa vivipara, Studer. Sexes separate. 



3. O. brevirima, H. L. Clark. Sexes separate. 



