10.  VESPERTILIO.—­Little black Bat.

This diminutive little animal flew into my tent at the Depot, attracted by the light.  It is not common in that locality, or any other that we noticed.  It was of a deep black in colour and had smaller ears than usual.

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BIRDS.

I have observed that a principal reason I had for supposing that there was either an inland sea, a desert country, or both in the interior, was from observations I had made during several expeditions, and in South Australia, of the migration of certain of the feathered tribes to the same point—­that is to say, that in lat. 30 and in long. 144, I observed them passing to the N.W. and in lat. 35, long. 138, to the north.  Seeing, on prolonging these two lines, that they would pass over a great portion of the interior before they met, about a degree beyond the tropic, I concluded that the nature of the intervening country was not such as they could inhabit, and that the first available land would be where the two lines thus met.  It so happened that at the Depot, in lat. 29 1/2 and in long. 142, I was in the direct line of migration to the N.W., and that during our stay at that lonely post, we witnessed the migration of various birds to that quarter, though not of all.  This was more particularly the case with the water-birds, as ducks, bitterns, pelicans, cormorants, and swans,—­we saw few of the latter, but generally heard them at night passing over our heads from N.W. to S.E. or vice versu; but we never afterwards found any waters which we could suppose those birds could frequent in the distant interior.  On Strzelecki’s Creek a small tern was shot, and on Cooper’s Creek several seagulls were seen, but beyond these we had no reason to anticipate the existence of inland water from any thing we noticed as to the feathered races.  On our first arrival at the Depot there was a bittern, Ardetta flavicollis, that frequented the creek in considerable numbers.  This bird was black and white, with a speckled breast and neck.  Every evening at dusk they would fly, making a hoarse noise, to the water at the bottom of the Red Hole Creek, and return in the morning, but as winter advanced they left us, and went to the N.W.

About February and the beginning of March, the Epthianura tricolor and E. aurifrons, and some of the Parrot tribe, collected in thousands on the creeks, preparatory to migrating to the same point to which the aquatic birds had gone.  It was their wont to fly up and down the creeks, uttering loud cries, and collecting in vast numbers, but suddenly they would disappear, and leave the places which had rung with their wild notes as silent as the desert.  The Euphema elegans then passed us, with several other kinds of birds, but some of them remained, as did also the Euphema Bourkii, which the reader will find more particularly noticed under its proper head.