44 PEOCEEDINGS OP THE 



above it, with the addition of those which live at the depth from 

 which the net was withdrawn. Agassi^'s experiments also seem 

 to me to prove too much. His tow-nets came up always empty 

 from the intermediate zones. It is very singular that he should 

 not have caught even some of the dead bodies which, like rain, 

 drop constantly from the surface to the bottom. Further, so far 

 as fishes are concerned, there is no reason why certain forms 

 should not permanently inhabit intermediate zones, inasmuch 

 as also pelagic fishes are undoubtedly free swimmers for nearly 

 the whole of their life, without being tied to the proximity of 

 terra firma. The ova of many species which live in the mature 

 stage at the bottom of great depths are pelagic, and hatched at 

 or near the surface. The young continue to live for some time 

 under pelagic conditions {^Pla(jicsi(S, LeptocepliaU, Polyprion), but 

 as they grow they descend to the deep sea. It is very improbable 

 that this descent is rapid ; it must be gradual in order to allow 

 the physiological functions to get used to abyssal conditions ; or, 

 in other words, these fish must live for some time in mid- water. 

 Thus I consider that the question of the existence of a mid- 

 water fauna is still an open one, and one which can be decided 

 only by continued tow-net experiments in great depths of the 

 open ocean, with a bottom of clean ooze or mud. 



2. The Western Trojncal Pacific. 



Under this heading I include tlie work done by the ' Challenger ' 

 on her voyage from Tcugatabu all along the islands of the Eastern 

 Archipelago, thus skirting the Indian Ocean, and northwards 

 from New Guinea towards Japan. Thirty-one successful deep- 

 sea dredgings and trawlings were carried out; the richest in 

 species were those in tlie vicinity of the islands, from moderate 

 depths, though characteristic widely spread deep-sea forms 

 occurred even at short distances from land, where deep soundings 

 were obtained, as, for instance, in the Banka passage, north of 

 Celebes. The deepest sounding was ascertained about midway 

 between New Guinea and Japan, in 4475 fathoms. 



3. The Tropical Mid-Pacific. 



This was crossed by the ' Challenger ' from north to south, 

 from the Sandwich Islands, in or about Long. 150° "W. On 

 account of the uniform great depth the dredging operations were 

 attended wdth great diiEculties, and yielded numerically poor 

 results; eight dredgings, nearly all in greater depths than 2000 

 fathoms, w-ere successful. From a depth of 3000 fathoms a few 

 specimens were brought up with a number of manganese nodules, 

 sharks' teeth, ear-bones of Cetaceans, pumice-stones, with which 

 the bottom of this part of the Pacific seems to be strewn. The 

 deposits yielded an extraordinary number of Kadiolarians : 

 Haeckel enumerates from the deposit of one station in 2900 

 fathoms 267, and from another in 2425 fathoms 564 species. 



