September 19, 1895] 



NA TURE 



497 



ilid not call it so), extending from some fifty fathoms down to (in 

 our seas) one hundred or so. The upper liuiit of this zone is 

 Murray's mud-line. We come upon it in the deep fjord-like 

 sea-lochs on the west of Scotland, and in the Irish Sea to the 

 west of the Isle of Man. 



Now of these four zones, my experience is that the last — that 

 of the deep mud — has by far the poorest fauna both in species 

 and in individuals. The mud has a peculiar fauna and one of 

 great interest to the zoologist, but it is not a rkk fauna. It 

 contains some rare and remarkable animals not found elsewhere, 

 such as Calocaris tiiaiandreic^ Pattthalis oerstcdi^ l.ipobranckius 

 ieffnysi, Brissopsis lyrifcra, Amphiura chiajii, Isocardia (or, 

 and Sagar/ia herdiiiaiii : and a few striking novelties have been 

 described from it of late years, but we have no reason to believe 

 that the number of these is great compared with the number of 

 animals obtained from shallower w'aters. 



Dr. Murray not only insists upon the abundance of animals on 

 the mud, and its importance as the great feeding ground and 

 place of origin of life in the ocean, but he also (p. 1432) draws 

 conclusions as to the relative numbers of animals taken by a 

 single haul of the trawl in deep and shallow waters which can 

 scarcely be received, I think, by marine zoologists without a pro- 

 test. His statement runs (p. 1432) : " It is interesting to com- 

 pare single hauls maile in the deep sea and in shallow water 

 with respect to the numl)er of different species obtained. For 

 instance, at station 146 in the Southern Ocean, at a depth of 

 1375 fathoms the 200 specimens captured belonged to 59 genera 

 and 78 species." That was with a lo-foot trawl dragged for at 

 most two miles during at most two hours. Murray then goes 

 on to say : " In depths less than 50 fathoms, on the other hand, 

 I cannot find in all my experiments any record of such a variety 

 of organisms in any single haul even when using much larger 

 trawls and dragging over much greater distances." He quotes 

 the statistics of the Scottish Fishery Board's trawlings in the 

 North Sea, with a 25-foot trawl, to show that the average catch 

 is 7 "3 species of invertebrata and 8 '3 species of fish, the greatest 

 number of both together recorded in one haul being 29 species. 

 Murray's own trawlings in the West of Scotland gave a much 

 greater number of species, sometimes as many as 50, "still not 

 such a great variety of animals as was procured in many instances 

 by the Challenger's small trawl in great depths." 



Now, in the fir.st place, it is curious that Murray's own table 

 on p. 1437, in which he shows that the " terrigenous" deposits 

 lying along the shore-lines yield many more animals, both 

 specimens and species, jier haul, than do the " jielagic " deposits ^ 

 at greater ilepths, such as red clays and globigerina oozes, seems 

 directly opposed to the conclusion <juoted ai)ove. In the second 

 place, I am afraid that Dr. .Murray has misunderstood the 

 statistics of the Scottish Fishery Board when he quotes them as 

 showing that only 7 "3 or so species of invertebrates are brought 

 up, on the average, in the trawl net. I happen to know from 

 Mr. Thomas Scott, F.L.S., the naturalist who has compiled 

 the statistics in question, and also from my own observations 

 when on board the Garland on one of her ordinary trawling 

 expeditions, that the invertelirata noted down on the station 

 sheet are merely a few of the more conspicuous or in other ways 

 noteworthy animals. No attempt is made — nor could possibly 

 be made in the time — by the one naturalist who has to attend 

 to tow-nets, water-bottle, the kinds, condition, food, &c., ofthe 

 fish caught ami other matters — to give anything like a complete 

 or even approximate list of the species, still less the number of 

 individuals, brought up in the trawl. I submit, therefore, that 

 it is entirely misleailing to compare those Scottish Fishery 

 Board statistics, which were not meant for such a purpose, but 

 only to give a rough idea of the fauna associated with the fish 

 upon certain grountls, with the carefully elaliorated results, 

 worked out at leisure by many specialists in their laboratories, 

 of a haul of the C/ial/enger's trawl. Of Dr. Murray's own 

 iKiwIings in the West of Scotland I cannot, of course, speak so 

 Ijusitively ; but I shall bo surprised to learn that the results of 



' One of [he L-.irliest of the Challenger oceanographic results, the classi- 



itioii of the suhniariiie tieposils into "terrigenous" and "pelagic," seems 



tilequate to represent fully the facts in regard to sea-hottoms, so I am 



]u>iJosinK elsewhere ("Report of Irish Sea Committee") the following amended 



' l.i^^itication :— (i) Terrigenous (Murray), where the deposit is formed chiefly 



"t mineral panicles derived from the waste of the land ; (2) Neritic, where 



' ' deposit is chiefly of organic origin, and is derived from the shells and 



' li'T hard parts of the animals and plants living on the hottom ; (3) Plank- 



iic (Murray's " pelagic "), where the greater part of the deposit is formed 



Ml the remains of free-swinuiiing animals and plants which lived in the sea 



over the deposit. 



NO. 135 I, VOL. 52] 



each haul were as carefully preserved and as fully worked out 

 liy specialists as were the Challenger collections. 



Lastly, on the next Liverpool Marine Biology Com- 

 mittee's dredging expedition in the Irish Sea after the 

 appearance of Dr. Murray's volumes, I set myself to determine 

 the species taken in a haul of the trawl for comparison with the 

 Challenger numbers. The haul was taken on June 23, at 

 7 miles west from Peel, on the north bank, bottom sand and 

 shells, depth 21 fathoms, with a trawl of only 4-foot beam, less 

 than half the size of the Challenger one, and it was not down 

 for more than twenty minutes. I noted down the species ob- 

 served, and I filled two bottles with undetermined stuff" which 

 my a.ssistanl, Mr. Andrew Scott, and I examined the following 

 day in the laboratory. Our list comes to at least 112 species, 

 belonging to at least 103 genera.' I counted 120 duplicate 

 specimens which, added to 112, gives 232 individuals, but there 

 may well have been 100 more. This experience, then, is very 

 different from Murray's, and gives far larger numbers in every 

 respect — sjjecimens, species, and genera — than even the Chal- 

 lenger deep-water haul quoted. I append my list of species, - 

 and practised marine zoologists will, I think, see at a glance 

 that it is nothing out of the way, that it is a fairly ordinary 

 assemblage of not uncommon animals such as is frequently met 

 with when dredging in the "coralline" zone. I am sure that 

 I have taken better netfuls than this both in the Irish Sea and 

 on the West of Scotland. 



In order to get another case on different ground, not of my 

 own choosing, on the first occasion after the publication of Dr. 

 Murray's volumes, when I was out witnessing the trawling ob- 

 servations of the Lancashire Sea Fisheries steamer fohn Fell, I 

 counted, with the help of my assistant, Mr. .\ndrew .Scf>tt, and 

 the men on board, the results of the first haul of the shrimp 

 trawl, It was taken at the mouth of the Mersey estuary, inside 

 the Liverpool bar, on what the naturalist would consider very 

 unfavourable ground, with a bottom of muddy sand, at a depth 

 of 6 fathoms. The shrimp trawl (li-inch mesh) was down for 

 one hour, and it brought up over seventeen thousand specimens, 

 referable to at least 39 species,^ belonging to 34 genera. These 

 numbers have been exceeded on many other hauls taken in the 

 ordinary course of work by the Fisheries steamer in Liverpool 

 Bay — for example, on this occasion the fish numbered 5943, and 



1 have records of hauls on which the fish numbered over 20,000, 

 and the total catch of individual animals must have been nearly 

 50,000. Can any of Dr. Murray's hauls on the deep mud beat 

 these figures ? 



The conclusion, then, at which I arrive in regard to the dis- 

 tribution of animals in deep water and in water shallower than 

 50 fathoms, from my own experience and an examination of the 

 Challenger results, is in some respects the reverse of Murray's. 

 I consider that there are more species and more individuals in 

 the shallower waters, that the deep mud as dredged has a poor 

 fauna, that the " Coralline " zone has a much richer one, and 

 that the " Laminarian " zime, where there is vegetable as well 

 as animal food, has probably the richest of all. 



In order to come to as correct a conclusion as possible on the 

 matter, I have consultetl several other naturalists in regard to 

 the smaller groups of more or less free-swimming Crustacea, 

 such as Copepoda and Ostracoda, which I thought miglit pos- 

 sibly be in considerable numbers over the mud. I have asked 

 three well-known specialists on such Crustaceans — viz.. Prof. 

 G. S. Brady, F.R.S., Mr. Thomas Scott, F.L.S., and Mr. I. C. 

 Thompson, F. L.S. — and they all agree in stating that, although 

 interesting and peculiar, the Copepoda and Ostracoda from the 

 deep mud are not abundant either in species or in individuals. 



' It is interesting, in connection with D.trwin's opinion that .in animal's 

 most formidable competitors in the struggle for existence are those of its 

 own kind or closely allied forms, to notice the large proportion of gener.1 to 

 species in such hauls. I have noticed this in many lists, and it certainly 

 suggests that closely related forms are comparatively rarely taken together. 



2 See Appendix, p. 501. 

 Mytiliis cdulis 

 Tellina tenuis 

 Mactra stultomm 

 Fltstts antiquus 

 Carcinus ntiritas 

 rortitnns, sp. 

 Kupngurus hernhardui 

 Crangon z-iilgaris 



' Sacciilina, sp. 



3 'iolcft vulgaris 

 Pleuronectes plaiessa I 

 /-*. limanda \ 



Cadus morrhua 

 G. ocgU'pinus 

 G. merlangus 

 Clupea sfralta 

 C hare*. 



nareugus 

 Trachinus vipcra 



Agoitus cataphraetus Some Amphipoda 

 Gol'ius minutus \ Lougiptdia coroHata 



Kaia elavata Ect:»oso»ta spiuipcs 



A*, maculata Sunaristes paguri 



Dactyhpus rostratxts 

 Cletodcs iiinicola 

 Caligus, sp. 

 Flustra/oliaeea 

 Aphrodite aculeata 

 Pcetiuaria bclgiea 

 Xereis, sp. 

 Astcrias ntdeus 

 Hydractinia eehinaia 

 Sertularia abietina 

 Hydrallmania/uUata 

 Aurclia aurita 

 Cyanaa, sp. 



