lO 



Pratt, Bipolar Theory. 



5- Priapuioides austral is, De ^. Priapuloides typicus, Kor. 



Guerne. & Ij)^n, 



Tierra del Fuego. Greenland, Iceland, 



Spitzbergen, Nor- 

 way. 



Of five species of Gephyrea taken in southern waters, 

 two {Phascolosouia inargaritaceum* and Priapulus 

 caudatus) occur also in northern seas ; two {^Echiurus 

 chiiensis and Priapuloides australis) are represented in 

 northern waters by the closely allied species Echitirus 

 unicinctus and Priapuloides typicus ; whilst one southern 

 form has not been taken in the northern hemisphere. 



In the distribution of these species of Gephyrea and 

 the ^enus Echiuj-us, which have not been taken in the 

 tropics, we have no evidence of an interpassage of species 

 along the western shores of America or Africa. 



An interesting list of nine extra-tropical species of 

 Polychaeta from the Straits of Magellan is given by Ehlers 

 ('96, p. 11). Of them, three occur also in Arctic waters: 



• Pkascolosoiiia ntargaritaceum was taken by Sars, presumably oft" 

 Norway, at a depth of 300 fathoms, but it has not been taken at any depths 

 at intermediate stations between Ireland and the Straits of Magellan, so we 

 must regard it as extra-tropical. 



