,"370 M. L. D'Albertis on Birds collected during 
time this bird has been met with in New Guinea, and that it 
was believed to be an inhabitant of the Aru Islands only. 
The fact of two species so alike living in the same locality is 
of some interest, and suggests some remarks. There are now 
four species of the known genus Paradisea —viz. P. apoda , P. 
papuana, P. rubra , and P. raggiana. The former two re¬ 
semble each other very closely in the long yellow plumes at 
the side of the breast, while the last two resemble each other 
in the red colour of the same plumes, but differ in the two 
middle tail-feathers &c. So far as we know, P. apoda in¬ 
habits the Aru Islands and the mainland of New Guinea, 
south of the Charles-Louis Mountains ; Paradisea papuana , 
the west to 131° long. E., and north of the above-mentioned 
range, so far as 141° long. E., and other islands north of New 
Guinea. The two red species, on the other hand, are living 
very far from each other; the P. rubra seems confined to 
Waigiou Island, and P. raggiana to the centre and eastern 
peninsula of New Guinea. But it is not improbable that 
P. rubra also may be found some day in New Guinea. 
From the first insight we have of the fauna of Southern 
New Guinea, we have learned how in this part of the country 
Australian forms, genera, and species are abundant, and are 
generally found in preference to allied species now inhabiting 
the north-western coast; and I think that what applies to 
the animals will be also found in a less degree to apply to the 
plants. So we find a larger number of species inhabiting 
North Australia, Aru Islands, and New Guinea, because the 
narrow sea which separates the three countries may be easily 
crossed even by birds of not very great power in the wings. 
So far as I can guess from my last visit to the central part 
of New Guinea, as well as from some fossils there collected, 
I think that all the flat land from the coast of Torres Strait 
up, perhaps, to the foot of the mountains has been submerged, 
and raised again at a not very distant time, and probably 
when the Aru Islands and Australia were separated from New 
Guinea. Plants and animals which, during the time of sub¬ 
sidence, could live on the mountains, at the new rising of the 
land descended to populate it again, more or less modified; and 
