IOO 



TH. MORTENSEN, 



(Schwed. Siidpolar-Exp. 



Zoogeographical remarks. 



In the sEchinoiden der deutschen Siidpolar-Expedition» (p. 92 — 105) a general 

 account of the Zoogeography of the antarctic-subantarctic Echinoid-fauna is given, 

 the main results being the following: The South American (Patagonian-Chilian) 

 littoral region must be regarded as the centre of the" whole antarctic-subantarctic 

 region; a very great proportion of the Echinoids occurring in the Patagonian region 

 are known from this region alone, while others are known also from the Antarctic 

 region (Arbacia Dufresnii, SterecJiinus Neumayeri, Abatus cavernosusQ) and Austro- 

 cidaris canaliculata (?)). This bears testimony of a former connection between South 

 America and the Antarctic Continent; especially the occurrence of the viviparous 

 genus Abatus in both these regions is conclusive evidence of such a connection, even 

 if it be ultimately proved that the species caver nosus does not really occur at the 

 antarctic coast. Further the Echinoids prove that the Kerguelen-group also belongs 

 to the Patagonian region; the occurrence there of Abatus cordatus, very nearly related 

 to the Patagonian species Abatus cavemosus and A. Agassizii, and of Eurocidaris nutrix, 

 nearly related to the Patagonian Austrocidaris canaliculata points to the existence of 

 a former land or shallow water connection between Kerguelen and South America; 

 especially the Abatus species, being viviparous and a littoral species, cannot possibly 

 have come to Kerguelen over the vast deep sea now separating this group of islands 

 from South America. Also a transportation on algae, 1 which might be possible for 

 Eurocidaris, is excluded for this species. 



To the Echinoid fauna of South Africa and New Zealand the Patagonian fauna 

 has no relation whatever, 2 a fact in direct contradiction to the hypothesis of a former 

 land connection between these regions, directly or indirectly (over the antarctic con- 



1 I may recall the observation of Protocenlrotus angulosus carried on floating algae in the Atlantic 

 recorded in the »Echinoiden d. deutschen Siidpolar-Exped. » p. 61. 



2 The occurrence of a species of the genus No/echinus at New Zealand (Stewart Island) (cf. p. 40, 

 Note) cannot give evidence for the supposed land connection with South America. The genus Notechinus 

 is widely distributed in the subantarctic region, and has most probably pelagic larvae, which may be trans- 

 ported by the currents. — I may here also recall the fact that the quite recent indication by Rudmose 

 Brown of the occurrence of ■» Goniocidarist canaliculata at South Africa has proved to be erroneous, being 

 due to a wrong determination (cf. p. 19. Note). 



