52 
velvet-like line of hairs along their inner edges. The 
rest of the ambulatory legs are much shorter, and all 
bear chelze, a character which will demand a certain re- 
laxation of the diagnosis of the Astacidze if Deidamia is 
to be placed in that family. 
The specimen captured being a male, the first pair of 
swimmerets are somewhat modified. The four other 
pairs of swimmerets, which are 33 mm. in length, bear 
each two narrow swimming processes richly fringed with 
hair, and a short flagellum. 
The absence of eyes in many deep-sea animals and 
their full development in others is very remarkable. I 
have mentioned (“The Depths of the Sea,” p. 176), the 
case of one of the stalk-eyed crustaceans, Ethusa 
granulata, in which well-developed eyes are present in 
examples from shallow water. In deeper water, from 110 
to 370 fathoms, eye-stalks are present, but the animal is 
apparently blind, the eyes being replaced by rounded 
calcareous terminations to the stalks. In examples from 
500 to 700 fathoms in another locality, the eye-stalks have 
lost their special character, have become fixed, and their 
terminations combine into a strong pointed rostrum. In 
this case we have a gradual modification, depending ap- 
parently upon the gradual diminution and final disappear- 
ance of solar light. On the other hand, Wznzda, from 
equal depths, has its eyes unusually developed and appa- 
rently of great delicacy. Is it possible that in certain 
cases, as the sun’s light diminishes, the power of vision 
becomes more acute, while at length the eye becomes 
susceptible of the stimulus of the fainter light of phos- 
phorescence? The absence of eyes is not unknown 
among the Astacide. Astacus felluctdus, from the 
Mammoth Cave, is blind, and from the same cause—the 
absence of light ; but morphologically the eyes are not 
entirely wanting, for two small abortive eye-stalks still 
remain in the position in which eyes are developed in all 
normal decapods. In Deidamia no trace whatever 
remains either of the eyes of sight or of their pedicels. 
On Thursday the 6th we sounded in 2,325 fathoms, 
sending down a thermometer and the slip water-bottle. 
The temperature registered was 1°°7 C., and the specific 
gravity of the sample of water was 102470 at 21° C., that 
of the surface water being 1'02556, at 23°°3 C. 
A good deal of gulf-weed drifted past during the day, 
and a boat was sent out to collect some. About half a 
dozen closely twined bundles were procured, and on 
examining them it was found that the bundle was bound 
together by strings of the viscid secretion of Antennarius 
marmoratus, and formed a nest containing the eggs of the 
fish. Several young examples of this grotesque little 
animal have been from time to time brought in among 
the gulf-weed ; also many crustaceans, several of the 
nudibranchiate mollusca characteristic of the gulf-weed 
fauna, suchas Scz//@a pelagica p., and many planarians, 
The dredge came up at 4.15 P.M. with a small quantity 
of red mud, in which we detected only one single but per- 
fectly fresh valve of a small lamelli-branchiate mollusk. 
In the mud there were also some sharks’ teeth of at least 
two genera, and a number of very peculiar black oval 
bodies about an inch long, with the surface irregularly 
reticulated, and within; the reticulates closely and sym- 
metrically granulated the whole appearance singularly 
like that of the phosphatic concretions which are so 
abundant in the greensand and trias. My first impres- 
sion was that both the teeth and the concretions were 
drifted fossils, but on handing over a portion of one of the 
latter to Mr. Buchanan for examination, he found that it 
consisted of almost pure peroxide of manganese. 
The character both of the exterior and interior of the 
nodule strongly recalled the black base of the coral which 
we dredged in 1,530 fathoms on the 18th of February ; 
and on going into the matter, Mr. Buchanan found not 
only that the base of the coral retaining its external or- 
ganic form had the composition of a lump of pyrolusite, 
NATURE 
[May 15, 1873 
but that the glossy black film covering the stem and 
branches of the coral gave also the reaction of manganese, 
There seemed to be little doubt that it was a case of slow 
substitution, for the mass of peroxide of manganese form- 
ing the root showed on fracture in some places the con- 
centric layers and intimate structure of the original coral, 
The coral, where it was unaltered} had the ordinary com- 
position, consisting chiefly of calcic carbonate. Whether 
the nodules dredged on March 7th are pieces of rolled 
coral, the ornament on their surface being due to an im- 
perfect crystallisation of the surface layer of the peroxide 
of manganese, or whether they form another case of 
pseudomorphy, the peroxide of manganese replacing some 
other organism, we have not the means of determining. 
The whole question is a very singular one, 
Some of our party, using the towing-net and collecting 
gulf-weed on the surface from a boat, brought in a num- 
ber of things beautiful in their form and brilliancy of 
colouring, and many of them strangely interesting for the 
way in which their glassy transparency exposed the work- 
ing of the most subtle parts of their internal machinery ; 
and these gave employment to the microscopists in the 
dearth of returns from the dredge. Our position was 
now lat. 19° 57’ N., long. 53° 26’; Sombrero distant 558 
miles. 
Sunday was a lovely day. The breeze had fallen off 
somewhat, and the force was now only from 2to 3. The 
sky and sea were gloriously blue, with here and there a 
soft grey tress on the sky, and a gleaming white curl on 
the sea. A pretty little Spanish brigantine, bright with 
green paint and white sails, and the merry, dusky faces 
of three or four Spanish girls, came in the morning within 
speaking distance and got her longitude. She had been 
passing and repassing us for a couple of days, wondering 
doubtless at the irrelevancy of our movements, shortening 
sail, and stopping every now and then in mid ocean with 
a fine breeze in our favour. On Monday morning we 
perted from our gay littlecompanion. We stopped again 
to dredge, and she got far before us, and we saw with 
some regret first her green hull and then her white sails 
pass down over the edge of the world. 
The sounding on Monday the toth gave 2,675 fathoms, 
with a bottom of the same red clay with very little cal- 
careous matter. The bottom temperature was 176 C., 
that of the surface being 23°°3C. We had been struck 
for some time past with the singular absence of the 
higher forms of life. Not a bird was to be seen from 
morning to night. A few kittiwakes (Larus tridactylus) — 
follewed the ship for the first few days after we left Tene- 
rifie, but even these had disappeared. A single petrel 
(Thalassidroma pelagica) was seen one day from one of 
the boats on a towing-net excursion, but we had not seen 
one of the southern sea-birds. For the last day or two 
scme of the larger sea-mammals and fishes had been 
visible. A large grampus (Orca gladiator) had been 
moving round the ship and apparently keeping up with 
it. Some sharks hung about, seeking what they might 
devour, but we had not yet succeeded in catchin 
any of them. Lovely dolphins (Coryphena Perot) 
passed in their varying irridescent colouring from the 
shadow of the ship into the sunshine, and glided about 
like living patches of rainbow. Flying-fish became more 
abundant, evidently falling a prey to the dolphins, which 
are readily deceived by a rude imitation of one of them, 
a white spinning bait, when the ship is going rapidly 
through the water. 
On Tuesday the 11th we pursued our course during the 
forenoon at the rate of from six to seven knots, with a 
light breeze, force 3 to 4. The dredge-line was veered to 
over 4,000 fathoms, nearly 5 statute miles. The dredge 
came up at about half-past five o’clock, full of red mud of 
the same character as that brought up by the sounding 
machine. Entangled about the mouth of the dredge and 
embedded in the mud were many long cases of a tube- 
