164 



deep water. It was either to escape their 

 enemies or to extend their range for 

 some reason ; as Mr. Garman puts it, 

 "They have sHd down," as it were to the 

 bottom of the ocean. 



In general, animals migrating will al- 

 ways move along lines of least resistance. 

 Some deep-sea fishes have a considerable 

 vertical range. It is thought that some 

 move into shallower water to deposit 

 their eggs or place their young in warm- 

 er water, and where the peculiar kind of 

 food they need early in life is the most 

 abundant. To study deep sea fishes is 

 difificult, and so little has been done that 

 we not only know them imperfectly but 

 also know very little concerning their life 

 histories. 



In February, March and April of 1891 

 the United States Fish Commission 

 steamer Albatross explored a portion of 

 the region between the coasts of Mexico 

 and Central America and the Galapagos 

 Archipelago. Besides obtaining a large 

 number of shore fishes, about nine hun- 

 dred specimens of fishes were secured, 

 ranging from a depth of one hundred to 

 twenty-two hundred and twenty-three 

 fathoms. This collection was carefully 

 studied by Professor Garman, of Har- 

 vard. He found the collection to contain 

 one hundred and eighty species, eighty- 

 five per cent, of which were new to 

 science. The bottoms of the oceans are 

 far from level, and each deep basin has 

 its own peculiar fauna. The shallower 

 parts of the sea prevent migration of the 

 deep water forms and no doubt living as 

 they do in eternal darkness and in a tem- 

 perature near the freezing point, there is 

 little to induce them to much activity. 

 The fact that they are easily captured in 

 nets of comparatively small size would 

 indicate that they move about slowly. 



Dr. Jenkins, who has lately studied the 

 fishes of the Sandwich Islands, informs 

 me that less than five per cent, are found 

 on our American coast, while a large per 

 cent, is found all the way to the Red sea. 



In other words, the fishes of the Sand- 

 wich Islands are East Indian rather than 

 American. This is no doubt caused from 

 the fact that the deep water between the 

 islands of the American coast forms a 

 barrier which has always prevented the 

 two fish faunas from mingling with each 

 other. Between Africa and the Sand- 

 wich Islands this has not been the case. 

 A recent study of the fishes of the Gala- 

 pagos Archipelago shows its fauna to be 

 American, though in what respect its 

 fishes dififer from those of our west coast 

 they resemble all the more the fishes of 

 the Sandwich Islands. Two fish faunas 

 will usually differ from each other if sep- 

 arated by an impassable barrier; espe- 

 cially is this true if the barrier be older 

 than the two faunas. 



Any barrier which prevents or hinders 

 fishes in their movements from one body 

 of water to another will separate two 

 more or less well-marked fish faunas. 

 These barriers may be mountains, or 

 shallow water, as in the case of deep sea 

 fishes ; deep water, as in case of shore 

 fishes ; muddy or alkaline water, or water 

 of different temperature. Temperature 

 no doubt has far more influence in gov- 

 erning the movement of fishes than is 

 generally believed. It plays an import- 

 ant part in guiding salmon up stream to 

 their spawning beds. It explains why 

 they reach the head waters of some 

 streams and spawn earlier than in similar 

 streams not far distant, but of different 

 temperature. If you would know to what 

 extent fishes of one region differ from 

 those of another, study well the barriers 

 between the two regions, learn to what 

 extent and how long they have existed, 

 consider the age geologically of the two 

 regions, and how fishes may have mi- 

 grated to one or the other, and in a gen- 

 eral way you will have the key to the sit- 

 uation, which a careful study of the fishes 

 is quite sure to verifv. 



Seth E. Meek. 



