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1876.] The Natural History of Kerguelen Island. — 483 
young developing directly into the adult form without the marked 
metamorphosis usual in echinoderms. 
In his able discussion of the structure and affinities of Chionis 
minor, the lesser sheath-bill, or “ white paddy ” of whalers, Dr. 
Coues has treated us to one of the most interesting ornithological 
essays that has appeared during the past few years. This bird 
is another instan ce, among the aberrant forms found in this island, 
of animals “ whose structure gives no clew whatever to their 
habits, so aberrant has been the progress of their variation in the 
peculiar conditions under which they live.” Thus the great south- 
ern skua has here adopted the habits of a land-hawk, and the 
lesser sheath-bill is “a connecting link, closing the narrow gap 
between the plovers and gulls of the present day. In our opinion, 
this group represents the survivors of an ancestral type from: 
which both gulls and plovers have descended. And this opinion 
is strongly supported by the geographical isolation of its habitat, 
affording but few conditions favorable to variation.’ 
In the practical matter of classification, it is evident that 
Chionis is not exactly referablé to either of the two groups be- 
tween which it stands. A consideration of its external charac- 
teristics, its digestive system, or its osteology, solely, would lead 
to very widely diverse conclusions. For we have presented in 
this bird a genus with the general appearance, gait, and flight of 
4 pigeon; with the beak and voice of a crow ; with the habits of 
a wader, yet dreading the water; and with the pugnacity and 
familiarity with man of a rasorial bird. With the last group its 
digestive system would certainly place it, to say nothing of the 
long after-shafts of the feathers ; and osteological comparison es- 
iy its position definitely between the gulls and the plovers, 
ut rather nearer to the former. 
The only land mammal found on the island is the common 
mouse (Mus n usculus), which abounds everywhere, and was 
doubtless MD ted by one of the early sealers. It builds its nest 
in holes in sand-banks, lining it with dried grass-stems or bits of 
» and appears to feed mostly on grass-seed. 
The sea-elephant is the most interesting marine mammal. It 
ins to “ haul up ” on the beaches of its breeding-places about 
October 10th, and remains ashore until well into the month of 
January, The old bulls, which alone are provided with a pro- 
9oscis, take charge, each, of a large number of females, guarding 
them from the approach of other bulls, and (so the sealers assert) 
Prevent them from returning to the sea before the young are old 
