FORAMINIFERA OF NORTH PACIFIC OCEAN. 17 



great ocean depths are very uniform, and it is in this portion of the 

 ocean basins that universal distribution is to be looked for. Many 

 species found at depths of 1,000 fathoms, for example, are probably to 

 be found in similar depths in any of the great ocean basins. This is 

 even more true of those species which are encountered at the 2,000- 

 fathom line. At depths of less than 500 fathoms species occur 

 which in many cases seem to have a rather limited range. Many such 

 species have been found — species, for example, which were recorded by 

 Brady from material from a single Challenger station, and have been 

 found again in the present study on the Albatross material from 

 exactly the same regions and at approximately the same depths. 

 Such species may be considered as marking definite fauna! limits 

 where enough such species occur in any one region. On this basis 

 the North Pacific Ocean may be divided up into several faunal 

 regions, which, while they may have a considerable number of species 

 in common, nevertheless have a distinctive character as a whole. 



Among the most characteristic of these faunas may be mentioned 

 the coral-reef fauna, as it may be conveniently called. This fauna, 

 characterized by such genera as Orbitolites, Alveolina, Peneroplis, 

 AmpMstegina, Polytrema, etc., is found about the coral reefs of the 

 Philippines, the Hawaiian Islands, Guam, and other of the tropical 

 oceanic islands of this area. It is best developed about the first two 

 groups of islands at comparatively shallow depths. In the north 

 this fauna extends, with certain modifications, up to the southern 

 portion of Japan, but so far as made out it is not developed at all 

 on the eastern coast of the North Pacific. The same fauna is found 

 in the Malay Archipelago, in various parts of the East Indies, off the 

 northern coast of Australia, to some extent in various parts of the 

 Mediterranean, and also a modification of it in the West Indies. 



Off the coast of Central America and Mexico there is developed a 

 peculiar fauna which is seen in a modified form in the deeper waters 

 off the eastern coast of the Philippines. Certain of the species, or at 

 least the genera, are also characteristic of certain parts of the extreme 

 North Atlantic, where they have been described by Brady from the 

 Porcupine and other dredgings. Some of the genera which are 

 characteristic of this region are Crithionina, Bathysiphon, large species 

 of Reophax, Verrucina, etc. 



Off the coasts of Japan and of the Philippine Islands in green mud 

 at depths of a few hundred fathoms there is another rather definite 

 fauna, which is mainly characterized by many species of the Lagenidse, 

 such as Sagrina bifrons H. B. Brady, and many of the species recorded 

 by Brady from the Hyalonema ground south of Japan in about 300 

 fathoms. This fauna appears to run northward a considerable dis- 

 tance along or off the Japanese coast and to extend eastward to the 



16777— Bull. 71—10 2 



