r 



TRE DEEP-SEA FAUNA, 



245 



Panamian. 



Gnathophausia willcmoesii (493-1270 fms.). 



■ '' brevispinis (551-1471 fms.). 



Eucopia australis (551-1770 fins.). 



Petaloplitlialmus pacificus (700 fins.). 



Gr. willemoGsii. S. of Amboiiia in Banda 

 Sea (1425 fms.). 



G. sarsii. Eay of Bengal (102 fms.). 



Bay of Bengal (C90-1748 fms.). 



North and Tropical Atlantic j Soutliern 

 Ocean ; Antarctic Ocean ; Japan ; Bay of 

 Bengal ; Gulf of Manaar (350-2500 fms.). 



P. armigcr. Tropical mid Atlantic (2500 

 fms.). 



p 1 





,1 



) * 



4 



:> 



s 



^\ 



A study of the deep-sea Crustacea thus leads to tlie conclusion that this 

 fauna is one of cosmopolitan range, indivisible into subordinnte local pro- 

 vinces like those of the littoral and terrestrial fauna). This is what one 

 would expect from the uniformity of conditions prevailing at great depths 

 and from the enormous length of time that has elapsed since modern types 

 of marine Invertebrata came into existence. We have seen not onlv that 

 many of the denizens of the cold waters of the intermediate zone, even with- 

 in the tropics, are emigrants from the shallow water o£ cold and cold-teniper- 

 ate latitudes, but also that very many of the peculiarly deep-sea types betray 

 their kinship with boreal genera. This, in the absence of much lif>-ht from 

 paleontology in this particular group of animals, may afford us the clew to 

 the origin of a large part of the abyssal Crustacean fauna. Earely, as in the 

 case of the recent Eryontidw, do we find a deep-sea type that vividly recall 

 an ancient form. In this case, so good an authority as Boas thinlcs that the 

 modern deep-water Pohjchdes is identical with tlie Jurassic Eryon. It is of 

 interest to note that in the same beds at Solenhofen — beds of undoubted 

 shallow-water origin — we find with ^E'ryon another singularly antiquated type 

 in Limulus. But the surviving descendants of Limulus are pre-eminently 

 httoral. It is manifestly illogical to assume, as some have done, that because 

 a certain form is now restricted to deep Avater the rocks in whicli it occurs 

 as a fossil were deposited at a similar depth. The surviving representatives 

 of an ancient shallow-water type may be littoral, as in the case of Limulus, 

 or they may be found ordy in deep water, like the recent Eryoiitidm. Some 

 mqnestionably bottom-living species at the present day have a vertical 

 distribution of 2000 fathoms. For instance, Parapagurus ahi/ssorwn ranges 

 from 250 to 2221 fathoms,^^ and Ball f states that certain species of Mollusca 



1 



* NoL taking into account tlio ^'Challenger" record 

 (Henderson, Rep. Clinllcnger Anouiura, p. 80, 18S8). 

 Bull. Mus. Couip. ZooL, XII. ]8G, 188G. 



of this species in 1-5 faihoms off Patngonia 



.'& 



