Dec. 9, 1869] 
NALDORE 
167 
5. Relation to Mollusca of the Gulf of Mexico.—\ hope 
soon, through the kindness of Professor Agassiz, to have 
an opportunity of examining and comparing the Mollusca 
dredged during the last three summers by Count Pour- 
tales in the United States expeditions. The only species 
which I have yet seen from the Gulf of Florida are 
Waldheimia Floridana and Terebratula Cubensis. The 
former appears to be that variety of Zerebratula septata 
(a Norwegian and now British species), which Professor 
Seguenza has described and figured under the name of 
Waldheimia Peloritana, from tertiary beds in Sicily; and 
the latter is closely allied to Zerebratula vitrea (Medi- 
terranean), and is perhaps a variety of that polymorphous 
species. Not only the external characters, but also the 
skeletons or internal processes of these American species 
correspond exactly with those of their European relatives. 
I must repeat that I am no believer in the doctrine or 
idea of species being “represented” in a geographical 
point of view. Species may be identical or allied, but not 
“representative.” 
6. Gulf Stream.—The northern character of the marine 
fauna observed during the Porcupine expedition is cer- 
tainly at variance with the general notion that this “ river 
in the ocean,” or any branch of it, flows directly to our 
coasts; and I have elsewhere * endeavoured to show that 
the occurrence in northern latitudes of tropical shells, 
seeds, and timber may be accounted for by the surface-drift 
arising from the prevalence of westerly winds. But there 
is unquestionably a marine as well as an aerial circulation, 
Equatorial and Arctic currents as well as Trade winds. 
7. Nature of the sea-bed.—In that part of my Report 
which contains a narrative of the expedition, so far as I 
was engaged init, I have given some particulars which it is 
unnecessary to recapitulate. Some of the pebbles and 
gravel from my deepest dredgings (1,215 to 1,476 fathoms) 
have been examined by Mr. David Forbes, the eminent 
mineralogist ; and he has kindly furnished me with the 
detailed report which I append to this communication. 
Among the pebbles and gravel were several fragments of 
true volcanic lava, which throw a considerable light on the 
course of the Arctic current along the western coasts of 
Ireland. He is of opinion that these volcanic minerals 
came from Iceland or Jan Mayen. Mr. Forbes has also, 
at my request, carefully and completely analysed a portion 
of the Atlantic mud from 1,443 fathoms, the pebbles and 
gravel having been previously removed from it by sifting; 
and the result shows that its chemical composition differs 
greatly from that of ordinary chalk. The sifted mud 
contains out of 100 parts 50°12 only of carbonate of lime, 
and no less than 26°77 of fine unsoluble gritty sand or 
(rock débris); while chalk consists almost entirely of car- 
bonate of lime, and seldom contains more than from 2 to 4 
per cent. of clay, silica, and other foreign material. But I do 
not say that this single analysis is conclusive. Mr. Forbes’s 
further report on that head, as well as on a specimen of 
Rockall (for which I am indebted to Staff-Commander 
Inskip, who procured it in the Porcupine surveying ex- 
pedition of 1862), also accompany this communication. 
I may observe that stony ground did not occur during 
the present expedition beyond about 550 fathoms, the 
sea-bed at greater depths being covered by mud or 
what is technically called “ ooze.” This superstratum 
appears to consist chiefly of decomposed animal matter 
mixed with the shells of Pteropods and G/odigerina, which 
must have dropped from the surface of the sea. I have 
myself seen living Glodzgerin@ in great abundance taken 
with Sfzvzales in the towing net; and Major Owen’s 
papers in the Journal of the Linnean Society for 1865 and 
1866 leave no doubt not only that Glodzgerin@ and other 
free Foraminifera live on the surface of the mid-ocean, 
but that they have the power, by protruding their pseudo- 
podia, of descending a few inches and rising again to the 
* “British Conchology,” vol. i. Intr. pp. xcviil. and xcix., and Report of 
British Association, 1868, p. 236, 
surface. Sessile or fixed Foraminifera, of course, cannot 
do this ; but I have found some of these living on the sur- 
face and attached to floating sea-weed (Fuews serratis) 
at a considerable distance from land. The fresh appear- 
ance of the sarcode in Foraminifera taken from great 
depths does not of itself prove that they live there, when 
we consider the comparatively antiseptic or preservative 
property of sea-water as well as the extremely minute 
size of the aperture in each cell which contains the sar- 
code. Some Foraminifera, however, inhabit only the 
bottom of the sea. 
8. Bathymetrical conditions.-So much has been said 
of late years (by myself among others) as to the 
depths of the sea being not merely inhabited but 
replete with life of a highly organised nature, and 
as to there being apparently no bathymetrical limit of 
habitability, I will content myself with noticing the Mol- 
lusca which were dredged in 2,435 fathoms. They 
were—(1) Pecten fenestratus, a Mediterranean species ; 
(2) Dacrydium vitreum, Arctic ; (3) Scrobicularia nitida, 
Finmark to Sicily; (4) Ve@va, an undescribed species, 
Norwegian ; and (5) Deztalium,a fine species, also un- 
described. The first of these species was known to inhabit 
depths varying from 40 to 60 fathoms, the second 50 to 
300 fathoms, the third 3 to 300 fathoms, and the fourth 
50 to 60 fathoms. The Dentalium is an inch and a half 
long ; and in 1,207 fathoms was taken a new species of 
Fusus, living and two inches in length. This last spe- 
cies, being one of a zoophagous tribe, must have had for 
its food prey of a suitable kind and perhaps of dimen- 
sions at least equal to its own. Abysmal life is not 
represented merely by microscopic organisms; and 1 
suspect that there is no difference in size between the 
animals that live in shallow water and the greatest depths. 
Nor do I believe that such abysses are dark or devoid of 
light. Colour is assuredly not wanting, nor the usual 
organs of sight in the Mollusca and Crustacea. Living 
specimens of the Dacrydium from 2,435 fathoms are red- 
dish-brown ; and a fine live specimen of 77ophon latericeus 
from 440 fathoms is bright rosecolour. Dacrydtum vitrenm 
makes a nest (like that of AZodtolaria discors and Lima 
hians) consisting of a narrow tubular case twice as long 
as itself. This case is lined with a delicate membrane, 
and covered with small Foraminifera, particles of sponge, 
and coccospheres, which are firmly agglutinated. The 
Dacrydium inhabits the broader half, its front or ventral 
margin lying in the direction of the opening of the case. 
From 2,090 fathoms came a new species of Plenvotoma, 
alive, and having a pair of prominent eyes on short stalks ; 
and the Fwsus from 1,207 fathoms was similarly provided. 
In both these genera the eyes are perfect and not rudi- 
mentary. The eyes of the Oxcopus from 632 fathoms 
are remarkably large and more highly organised than 
those of many fishes. The animals of this genus crawl 
with their arms, head downwards ; and the common species 
(O. vulgaris) buries itself in sand and gravel. Instances 
to prove that colour and visual organs are possessed by 
animals at very great depths are innumerable ; and they 
would lead us to infer that light (of what nature I can- 
not suggest) penetrates the sea to its profoundest base. 
None of the deep-sea animals appeared to be phosphores- 
cent. Perhaps in the next expedition some photometric 
apparatus may be devised in order to solve this problem. 
9. Oceanic currents.—The Arctic or Northern current 
probably runs with greater rapidity and force in some 
places than in others, where the flow seems to be very slow 
and feeble. Everywhere (as I pointed out in my Shetland 
Report for 1863) the motion must be extremely gentle or 
imperceptible at the bottom in deep water, as we find the 
most fragile and delicate corallines from stony ground 
quite uninjured. 
10. Geological considerations.—N ot the least interesting 
fact derived from this expedition was the discovery, in a 
living or recent state, of species hitherto supposed to be- 
