6 



W. LlLLJEBORG , 



more than one species can be named, that is common both to the Arctic 

 and Antarctic zones. This is the Falco peregrinus Lath., which has in- 

 deed received several different specific names, as the slight varieties of co- 

 lour which it displays in widely separated localities, have by some ornitho- 

 logists been looked upon as indicating different species, though for our 

 own part we cannot but agree with Schlegel l ) in considering these as me- 

 rely local varieties. The variety that occurs in North & South America has 

 been called Falco anatum Bonap. , and the Australian form has been named 

 Falco melanogenys GOULD. 



The fishes found in the fresh waters of Patagonia consist, it ap- 

 pears, only of two or three species of the Salmonoid family, as is also the 

 case with the fresh water fish belonging to the most northern fauna. 



Among the section of Mollusca are some instances which present the 

 phenomenon of an extensive geographical distribution, though their capabi- 

 lities for locomotion are very limited. Thus for example the Terebratula 

 caput serpentis is found from Spitzbergen to the Mediterranean and on the 

 eastern coast of North America, and the Rhynchonella Psittacea from Spitz- 

 bergen and Greenland to England, Massachussets and Siteha on the western 

 coast of N. America. Some species e. g. Saocicava arctica, Venus pidlastra 

 and Pecten pusio are found both on our northern coasts and at the Cape of 

 Good Hope though not in the intermediate tropical regions. We may per- 

 haps be able to show with certainty any species distinctly belonging to 

 the Arctic Zone, which also occurs in the Antarctic, though one or two 

 peculiar genera have been found that have their representatives in both 

 Zones. Bronn 2 J states that the species of Limacina which belongs to the 

 south Polar Ocean can not be distinguished from the Limacina arctica be- 

 longing to the northern, but it has by Woodward 3 ) been classed 

 parate species with the name Limacina antarctica. That genus has no re- 

 presentatives in the intermediate seas. The same is the case with the ge- 

 nus of Piinchtrella, which embraces two species, of which the one belongs 

 to the arctic the other to the antarctic seas (in the neighbourhood of Tierra 

 del Fuego). Of the genus Clio we have in the northern Polar Seas the Clio 

 borealis, which is there found in such plenty as to constitute a considerable 

 portion of the Greenland Whale's food. Passing over the intermediate oceans 



') Museum des Pay-Bas. 1 Livraison. Falcones. p. 1. 



2 ) Klassen und Ordnungen des Thierreichs. 3. Bd. p. 648. 



3 ) Manual of the Mollusca p. 207. 



