THE WEST INDIAN FAUNA. 9 



tical range of nine hundred fathoms or more. This vertical 

 range is probably limited to the bottom, except, perhaps, in the 

 case of pelagic fishes allied to deep-sea species, of which the 

 habitat is always uncertain. The majority of fishes, to be sure, 

 are bottom lovers when adult, but in larval stages, in the vari- 

 ous phases grouped by ichthyologists in the family Leptocepha- 

 lidse, they are carried by the Gulf Stream and other currents, 

 and spread far and wide over the ocean surface. Among the 

 flat fishes a transparent pelagic embryo flounder known as Pla- 

 gusia (see Fig. 78) passes under favorable circumstances into 

 a deep-sea flounder ; an allied species is known on the coast of 

 Italy as Rhombodichthys. 



It is an interesting problem to ascertain where the young of 

 these fishes remain before they become permanent inhabitants 

 of deep water. The same may be asked of some of the rarer 

 pelagic fishes occasionally caught at sea, which undoubtedly are 

 either fully grown deep-sea fishes or their young. 



The greatest depth from which fishes have been dredged by 

 the " Challenger " is 2,900 fathoms, and from that depth a sin- 

 gle specimen (Gonostoma microdon) was brought up. The "Al- 

 batross " obtained from a depth of 2,949 fathoms a closely allied 

 fish (Cydothone lusca, Fig. 196), and four others. The " Talis- 

 man " secured one species from a depth of 4,255 metres, and the 

 " Challenger " two from 2,750 fathoms, three from 2,500, and 

 one from 2,650. 



The larger part of the Crustacea, both in the West Indian 

 region and off the Atlantic coast of the United States, were 

 brought from a depth of less than 500 fathoms. Out of about 

 100 species of Brachyura, only two were dredged below 500 

 fathoms ; from about 75 species of Anomura, 22 were taken at 

 or below 500 fathoms, five below 1,000 fathoms, and one below 

 2,000 fathoms ; while among sixty species of Macrura thirty 

 are recorded as taken below 500 fathoms, and thirteen below 

 1,000 fathoms. 



The maximum range of the Crustacea does not seem to be as 

 great as that in other groups of invertebrates. In the Carib- 

 bean, only five species have a range of nearly 1,000 fathoms, 

 and about the same number one of 500 fathoms. 



