The Crinoidea of the Swedish Antarctic 
Expedition 
by 
Dr. TH. MORTENSEN. 
The collection of Crinoids brought home by the Swedish Antarctic Expedition 
is a small one, containing only five species. Nevertheless it is of quite unusual in- 
terest. Three of the five species are new to science; one of them represents a new 
genus, and even a new family, and shows some quite unique anatomical features. 
But, furthermore, all the three new forms are viviparous. 
While quite a number of viviparous forms have been known for a long time in 
all the other four classes of Echinoderms, especially from the Antarctic regions, not 
a single viviparous Crinoid was known hitherto, until in 1905 Dr. K. A. ANDERSSON 
described the first case of care of the brood in a Crinoid, which he had observed in 
one of the forms secured by the Swedish Antarctic Expedition, viz. that described in 
the present paper under the name of Isometra vivipara. 
Is was on account of a memoir on the development of some Crinoids, which I 
have under preparation, that I applied to Professor O. NORDENSKJÖLD for permission 
to work out the development of this species in order that I might include the report 
on it in the said memoir, Dr. K. A. ANDERSSON having previously informed me that 
he did not himself expect to get the opportunity to give the promised detailed account 
of the development of his viviparous Crinoid. Professor NORDENSKJÖLD not only 
readily granted my wish, but sent me the whole of the material of Crinoids collected 
by his Expedition, thinking that it might perhaps contain more to interest me. And 
so it proved, indeed, far beyond expectation, two more viviparous forms being found 
in the collection. 
It is truly wonderful thus to find three viviparous forms of Crinoids in this small 
collection, while not one has been found by any of the other Antarctic Expeditions, 
so far as known. That it is the Antarctic Sea that produces these viviparous forms 
i — 173534. Schwedische Südpolar-Expedition igoi — 1 goj . 
