94 
THE VOYAGE OF H.M.S. CHALLENGER. 
Disoovsky ur 
1 1 lull KH UK*. AN- 
IlMS IN GRRAT 
Dwnii*. 
* 
habitat Rhizopoda are more or less abundant in all seas, but the genus Globigenna 
m.iv I. regarded as essentially belonging to the deep sea, for it is found in all latitudes 
id ai all depths ; the point of its maximum development is in the greatest depths, where 
di p< -its made up of its dead remains stretch out for hundreds of square miles, forming 
p . L i lly deep beds. He endeavours to trace a connection between the Globigcrina 
( > ■ uid the Gulf Stream, pointing out that the shells are abundant in the deposits be- 
twccn the Faroe Islands and the east coast of Greenland, and in a large portion of the 
di ' i line between Cape Farewell and Rocka.il, but are absent or rare in the deposits be- 
tas, m Greenland and Labrador. In the southern hemisphere calcareous deposits had 
1 n found on the Agulhas Bank at a depth of 90 fathoms, in which the Globigerina 
sin IF made up 75 per cent, of the sediment ; he suggested that the area covered by this 
di ) ..-it depended on the current flowing round the Cape from the east. The only 
difference between the deposit in this and in other parts of the Atlantic is that the shells 
a iv more delicate in form, perhaps because the water is not so deep. He was unable to 
find in a tow-net dragged through nearly 700 fathoms of water a single Globigerina shell, 
a aerefore concludes that they live on the upper surface of the deposit at the bottom. 
Wallich attaches great importance to the discovery of members of the higher groups 
li \ : g at a depth of 1260 fathoms, about half-way between Cape Farewell and the north- 
w< • roast of Ireland. On examining the visceral cavity in a specimen of Ophiocoma, he 
noticed a number of GlobigerinsB more or less broken, amorphous particles, a few yellow 
oil jl"bulcs, and several ova. In three deep soundings he found Annelid tubes composed 
aim st entirely of small Globigerina shells, and in another case composed of minute 
r . i i • .i : . iou> debri and Sponge spicules in equal proportions. Ophiocoma granulata, found 
oti ie British and Scandinavian coasts in 10 to 50 fathoms, and off the coast of Green- 
land in 200 fathoms, was obtained from a depth of 1260 fathoms, without presenting any 
Lie modification, while the well-known littoral species,. Serpula vitrea and Spirorbis 
!,"■ tilovb s, were brought up from a depth of 680 fathoms. Wallich asks the questions : 
\\ . nee did these creatures originate? are we to regard the localities in which they were 
f i nd ;i - their genetic centres, or only as isolated colonies tenanted by species whose 
. t v cent r< - are to be looked for elsewhere ? and in answering them lie adopts the ideas 
■ . I- 1m s on the great changes which have taken place in the distribution of land and water 
deiing geological periods, supposing the submergence of a large tract in high latitudes of 
tie North Ytlantic. Jfe says : “ No proof of subsidence could be more complete, no proof 
-if tin truth of the doctrine of single specific centres more convincing, than the detection 
undi i uirli circumstances of a colony of acclimatized Star-fishes, belonging to a species 
ty, d of the Boreal province, well known to range from the confines of the Arctic circle 
t‘i > r own shores, and already shown to have accommodated themselves to a depth of 
2 0 f thorns without variation ; wdiilst the fact of subsidence being general throughout 
the v. i. h area i- rendered probable by the discovery of sessile Annelids, also belonging to 
