The Crinoidea of the Swedish Antarctic 



Expedition 



by 

 Dr. TH. MORTENSEN. 



The collection of Criuoids 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 famil}-, 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 NORDENSKJÜLD 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. Schvicdische Siutpolar-Expedition igoi — igoj. 



