374 



COMPARATIVE ZOOLOGY. 



of the food. Carnivores have a wider range than herbi- 

 vores. 



Life diminishes as we depart from the equator north 

 or south, and likewise as we descend or ascend from the 

 level of the sea. 



The zones of geography have been divided by zoolo- 

 gists into narrower provinces. Five vertical regions in 

 the sea have been recognized: the Littoral, extending be- 

 tween tide -marks; the Laminarian, from low water to 

 fifteen fathoms; the Coralline, from fifteen to twenty 

 fathoms ; the deep-sea Coral, from fifty to one hundred 

 fathoms ; and the Bathybian, from one hundred fathoms 

 down ; but since life has been found to extend to great 

 depths in the ocean — as great as three thousand fathoms 

 — these divisions are of little importance. Every marine 

 species has its own limits of depth. It would be quite as 

 difficult, said Agassiz, for a Fish or a Mollusk to cross 

 from the coast of Europe to the coast of America as for a 

 Reindeer to pass from the arctic to the antarctic regions 

 across the torrid zone. Marine animals congregate mainly 

 along the coasts of continents and on soundings. The 

 meeting -place of two maritime currents of different tem- 

 peratures, as on the Banks of Newfoundland, favors the 

 development of a great diversity of Fishes. 



Every great province of the ocean contains some repre- 

 sentatives of all the subkingdoms. Deep-sea life is diver- 

 sified, though comparatively sparse. Examples of all the 

 five invertebrate divisions were found in the Bay of Bis- 

 cay, at the depth of two thousand four hundred and thir- 

 ty-five fathoms. 192 



Distribution in the sea is influenced by the temperature 

 and composition of the water and the character of the 

 bottom. The depth acts indirectly by modifying the 

 temperature. Northern animals approach nearer to the 

 equator in the sea than on the land, on account of cold 



