16 THÉEL, PRIAPULIDS AND SIPUNCULIDS OF THE SWEDISH ANTARCTIC EXPEDITION 1901 — 1903. 



sation. — Now we have a new form of a Priapulus caught not far from La Plata- 

 river, tluis under temperate zones; this Priapulus is a genuine one, with all the 

 characteristic peculiarities, which mark this genus, but it differs from the other 

 representatives by its remarkably changed caudal appendage. Further on in my 

 paper, I have named it Priapulus horridus, and to my view it may be just such a 

 form which has been capable of sustaining the struggle for existence under subtropical 

 zones. Evidently it has not immigrated from colder zones. In all probability, it 

 ought to be looked on as a relicta from that period, when an uniform climate was 

 prewailing all över the world. 



Every scientific man who will examine the text and the drawings below 

 must understand, that that stränge form of a Priapulus is not to be derived 

 from a recent species now living in the polar seas, but that it must be a much 

 altered relict, its closest relatives having had less power of resistance and there- 

 fore having got löst. 



With regard to the Sipunculides which are mentioned further on in this paper, 

 I cannot state with the same conviction that they are bipolär in the same sense as 

 the Priapulids. To my knowledge, some of them have hitherto not been met with 

 anywhere but under the antarctic and subantarctic zones. But it may be otherwise 

 with regard to the remaining species: Phascolosoma margaritaceum (Särs) Ph. mi- 

 mitum Keferstein and Phascolion strombi (Mont.). Ph. margaritaceum belongs to 

 the cold northern regions and also occurs in the cold southern seas, but is ne ver 

 found under the equatoreal or subequatoreal zones. As to Ph. minutum (or 

 sabellarice), for first recorded from the coast of France, Heligoland and Sweden and 

 now, supposing I am right in my identification, also from the subantarctic region, 

 I think it likely that it may be found in the intermediate space, though owing to 

 its diminutiveness and mode of life, it has escaped our attention. It may possibly 

 be a cosmopolitan. 



The third species, Phascolion strombi, has a wide distribution in northern seas, 

 and long ago it is recorded from the coasts of Greenland, Spitzbergen, Sibiria, Scan- 

 dinavia, England, France, the Mediterranean and North America. If I am right in 

 my supposition that Verrill's Ph. tubicola is identical with it, then it also is found 

 off the coasts of West-India. Now, I have had at my disposal several forms, evi- 

 dently of this species, caught in the cold southern sea between South Georgia and 

 Falkland Islands. For the present our investigations are too imperfect to allow us 

 to state whether the species in question is a cosmopolitan too. As a matter of fact 

 none of the three species (except Ph. strombi) has hitherto been recorded from sub- 

 tropical seas, either from the west-coast of Africa or of that of America — and in 

 the deep-sea they certainly do not exist. 



When I undertook the investigation of the animals in question, I took it for 

 granted that very closely allied forms of a genus which lived in the two polar seas, 

 but not in the intermediate torried zones, must differ in some respects. For they 

 have been separate during an immense space of time and under conditions which 

 cannot have been quite the same. I therefore left no means untried to discover 



