January 21, 1892 J 



NATURE 



28' 



Our Crustaceans, from the nature of the bottom, naturally 

 consisted of the same groups of deep-sea types which we 

 obtained before. I may, however, mention a haul containmg 

 a goodly number of Nephrops, a genus we had not previously 

 obtained. 



Among the Worms the Maldan'se and I.imicolous types were 

 unusually abundant at some localities, the empty mud tubes 

 often filling the bottom of the trawl. Some very large speci- 

 mens of Trophonia were collected, and remarkably brilliantly 

 coloureH (orange and carmine) Nemerteans and Planarians. 



The Mollusks were very scanty, and the absence of Comatulae 

 ■or other Crinoids was equally disappointing, even when trawling 

 on the extension of the line started three years ago by the Alba- 

 tross, on the eastern face of the Galapagos slope, when on her 

 way from Chatham Island to San Francisco. We took up this 

 line off Indefatigable Island, hoping to obtain from that quarter 

 our best results, but our hauls were very disappointing. The 

 ground proved not only most difficult to dredge upon, but also 

 comparatively barren, and it was not till we got into the oceanic 

 basin again, between the Galapagos and Acapuico, that our 

 catches improved. But even then they were not to be compared 

 with the hauls at similar depths in the Atlantic off the West 

 Indies, or along the course of the Gulf Stream. 



Among the Fishes, our most important catches were fine speci- 

 mens of Bathyonus, of Bathybrissa, of Hathypteroides, and a few 

 specimens of Ipnops in excellent condition. 



From the nature of the bottom we naturally expected rich 

 hauls of Siliceous Sponges, but we did not find many, and I do not 

 think there were many novelties among those we have collected. 

 On two occasions, a number of specimens of Ascidians were 

 brought up ; among them was a fine white translucent Corina>^cidia. 



Among the Bryozoans, the most noteworthy haul was a 

 number of beautiful specimens of the delicate Naresia, in ex- 

 cellent condition. On the line from the Galapagos to Acapuico 

 we brought up a good many Foraminifera from the mud bottoms. 

 On several occasions the bottom must have been covered with 

 huge masses of a new type of an arenaceous Foraminifer, 

 forming immense curling sheets attached by one edge to stones 

 or sunk into the mud. This Foraminifer seems to increase in 

 size by forming irregular more or less concentric crescent-shaped 

 rings. W^hen it comes to the surface, it is of a dark olive-green 

 colour. 



During this second cruise we continued our experiments with 

 the Tanner closing tow-net, in oider to determine the lower 

 limits of the surface pelagic fauna, and to determine also if there 

 is any so-called intermediate pelagic fauna at other depths, or 

 within a short distance from the bottom. 



On March 25, at a point not quite half-way between Cape 

 San Francisco and the Galapagos, in 1832 fathoms of water, the 

 Tanner net was sent down to tow at a depth which varied from 

 1739 to 1773 fathoms. The net was towed within these limits 

 for a period of something over twenty minutes. The messenger 

 was then sent down to close the net ; lime occupied seven 

 minutes. The net was then drawn up to the surface. The 

 lower part of it was found to have closed perfectly, and contained 

 nothing beyond a few fragments of leaves. The lower bag was 

 carefully washed in water which had been strained, and the 

 water examined with all possible care, and sifted again. It con- 

 tained nothing. The upper part of the net, however, which had 

 remained open on its way up, was found to contain the identical 

 surface things which on former occasions we had found in the 

 Tanner net down to a depth of 200 fathoms. They were a 

 small species of Sagitta, and species of Doliolum, Appendi- 

 cularia, a huge Sagitta, a large number.of Leucifer and Sergestes, 

 and several species of Schizopods and Copepods ; two species 

 of Hyperia, probably parasitic on a Salpa, which was also quite 

 abundant ; several finely coloured Calanus, some Isopods, and a 

 number of fragments of what must have been a very large Beroe, 

 measuring from five to tix inches in diameter ; Leptocephalus, 

 several specimens of Stomias, of Scopelus, of Melamph<Es, and 

 other species, many of which, like some of the Schizopods, had 

 been considered as typical deep-sea forms. Among the so-called 

 deep-sea Meduste, several specimens of Atolla and Periphylla 

 were also found in the open part of the net. I may mention 

 also as of special interest a huge Ostracod, allied to Crosso- 

 phorus, with a thin semi-transparent carapace, and measuring 

 somewhat more than one inch in length. The largest Ostracod 

 previously known is not more than one-third of an inch long. 

 On two other occasions this same Ostracod was brought up in 

 the tow-net from a depth of less than 200 fathoms. 



NO. II 60, VOL. 45] 



The surface at this point was also examined with the tow- 

 net, and the pelagic animals found to be the same as those brought 

 up in the open part of the tow-net on its way from the bottom. 

 The number both of species and specimens was, however, much 

 less than in the Tanner net. On the following day the Tanner 

 tow- net was sent to be towed at a depth of 214 fathoms. In 

 twenty minutes the messenger was sent down and the net hauled 

 up. The bottom part of the net came up tightly closed. Its 

 contents were examined in the same manner as before in well 

 sifted water, and the water was found to be absolutely barren, 

 while the upper part of the net, which came up open, and was 

 not more than eight or nine minutes on the way, was well filled 

 with surface life. The net contained this time a number of 

 Hyalseas and Criseis, in addition to the things collected the day 

 before. An examination of the surface fauna at this same point 

 with the tow-net showed the presence only in smaller numbers 

 of the same species which the open part of the same net contained, 

 except that there were a larger number of bells and fragments 

 of Diphyes and of Cristalloides than in the Tanner net. The 

 point at which this experiment was made was about 250 miles from 

 the Galapagos, and about the same distance from Cape San 

 Francisco. There were myriads of Nautilograpsus swarming 

 on the surface of the water ; they literally filled the surface tow- 

 net. On two other occasions, once at a distance of 350 miles in a 

 south-easterly direction from Acapuico (depth 2232 fathoms), 

 we tried the same experiment with the Tanner net, and in- 

 variably with the same result. The net was towed at a depth 

 of 100, of 200, and of 300 fathoms, each time for twenty 

 minutes, the messenger sent down, and the bottom part closed. 

 At the depth of 100 fathoms, the closed part of the net con- 

 tained practically the same things as the open part of the net ; 

 at 200 fathoms, the lower part of the net contained but few 

 specimens of the surface life ; and at 300 fathoms, the closed 

 bottom net came up empty. 



On the following day the surface was carefully examined, and 

 the tow net sent to 175 fathoms, where it was towed for twenty 

 minutes, and the messenger sent down to close it. The losyer 

 net came up well filled with the surface pelagic species, which 

 on this day were unusually varied, it having been smooth and 

 calm the previous night, and the morning before the towing was 

 made. This haul was made in the evening, at 8 p.m. The 

 previous hauls had been made at about 10 a.m., in a brilliant 

 sunlight. Again, on April il, about thirty miles south-east of 

 Acapuico, in a depth of over 1800 fathoms, the Tanner net was 

 sent to a depth of 300 fathoms, and the messenger sent down to 

 close it. There was nothing in the lower part of the net which 

 had been closed, while the open part contained an unusually 

 rich assortment of surface species, and among them a large 

 number of Scopelus, of Schizopods, and of Rhizopods, mainly 

 Collozoun and Acanthometra. 



These experiments seem to prove conclusively that in the open 

 sea, even when close to the land, the surface pelagic fauna does 

 not descend beyond a depth of 200 fathoms, and that there is 

 no intermediate pelagic fauna living between that depth and the 

 bottom, and that even the free-swimming bottom species do not 

 rise to any great distance, as we found no trace of anything 

 within 60 fathoms from the bottom, where it had been fairly 

 populated. 



The experiments of Chun regarding the distribution of the 

 pelagic fauna have all been made in the Mediterranean, within 

 a comparatively short distance from the shore, and in a closed 

 basin showing, as is well known, special physical conditions, its 

 temperature to its greatest depths being considerably higher 

 than the temperature of oceanic basins at the limit of 200 

 fathoms, or thereabout, which we assume now to be the limit 

 of the bathymetrical range of the true oceanic pelagic fauna. 

 At 200 fathoms our temperature was from 49" to 53', while, as 

 is well known, the temperature of the Mediterranean soon falls 

 at 100 fathoms even to about 56°, a temperature which is con- 

 tinued to the bottom in this closed basin. Of course, if tem- 

 perature is one of the factors affecting bathymetrical distribution, 

 there is no reason except the absence of light which vvould 

 prevent the surface pelagic fauna from finding conditions of 

 temperature at the greatest depth similar to those which the 

 surface fauna finds within the limit of 200 fathoms in an open 

 oceanic basin. _ . 



Arriving as we did at the Galapagos at the begmnmg of a 

 remarkably early rainy season, I could not help contrasting the 

 green appearance of the slopes of the islands, covered as they 

 were by a comparatively thick growth of bushes, shrubs, and 



