]918] Essoihcrg: Distribution of tJte Polynoidae 205 



liad migrated from southern latitudes, while in the greater depths 

 exclusively arctic species predominated. 



The observations of investigators in other fields of animal life 

 strongly support the view that to a great extent temperature deter- 

 mines the distribution of oceanic fauna. The studies on Dinoflag- 

 ellata prove that certain species of Gonyaulax (Kofoid, 1907, 1911) 

 may be designated as distinctly warm water forms occurring in the 

 warm waters of the tropical and subtropical zones on this coast as well 

 as in other oceans, while the species occurring in the subboreal regions 

 on this coast are also reported from other parts of the world from 

 the cold waters. The ascidians of this coast (Ritter, 1913) are dis- 

 tinguishable as boreal, subboreal, and temperate species, each group 

 being limited strictly to its temperature zones. 



Furthermore, we find that the same temperature relations prevail 

 in the distribution of terrestrial fauna and flora. Contrasting the 

 valleys and mountains, where the difference in temperature is con- 

 siderable, we find that many species of animals are restricted to valleys 

 in higher latitudes which in lower latitudes in tropical areas, inhabit 

 higher altitudes or the alpine zones; while the lowland species of a 

 subtropical or tropical zone do not ascend to the higher altitudes of 

 that latitude. Oregon lowland forms of insects extend southward 

 into California where they seek a higher altitude. Some species, like 

 Tragosoma harrisii, occur from Sitka to California. In the cooler 

 regions in the higher latitudes, they are found in lowlands. They rise 

 as they approach a more southern region until in the subtropical Cali- 

 fornian areas they inhabit the zones above 10,000 feet altitude 

 (Cockerell, 1893). Furthermore, some Coleoptera which occupy the 

 lowlands in temperate zones occur as alpine species in the Andes in 

 Ecuador and are never found in tropical lowlands. Some Coleoptera 

 which occur as alpine and subalpine species in the tropical and sub- 

 tropical areas of North America are found in Canada, Lapland and 

 other northern countries as lowland species. 



Comparing the high-alpirie, mid-alpine and subalpine species of 

 insects of tropical zones we find again that each zone has its distinct 

 species which do not occur in the adjacent zones. The level at which 

 certain species may be found varies with the season, the line rising 

 up the hill during summer and receding towards the valley in Avinter. 

 The valleys and the mountains on the dry land, as far as the tem- 

 perature is concerned, are comparable to the shallow and deep waters 

 in the oceans. The effect on distribution is comparable in the two 

 cases. 



