ox 
Sa THE GEELONG NATURALIST.* 
The discovery of Argon—the new gas forming a small, 
though constant, and not unimportant, portion of the atmos- 
phere,—has led to experiments by Mr. G. W. MacDonald, a 
Melbourne science graduate now studying in London. In a 
paper read before the Royal Society (London), he states that 
no argon is distinguishable in the vegetable and animal 
tissues on which his experiments were made. 
NOTES ON THE LITTLE TERN AND SPINE- 
mie TAILED SWIFT. 
By J. F. MULDER. 
Tue Australian Little Tern (Sternula nereis). This pretty 
little **Sea Swallow,” as some people call it, is less than 
nine inches long, and weighs about two ounces, and it measures 
twenty inches from tip to tip of the wings. The under portion . 
of the body is of a beautiful spotless white, while the upper 
part and the wings are of a pale slate colour, becoming 
darker on the primaries. In the bird before me there is a 
black patch on the nape extending to the front of the eye, 
crown of the head pale brown, eyes black, and legs light 
brown. „This bird proved, on dissection, to be a female; in 
the male the top of the head is black, and I have seén 
examples in which the feathers on the breast were of a dark 
grey tinged with brown. The legs are very short and weak, 
which we should expect from the habits of the bird, it being 
almost constantly on the wing, but, unlike the swift and 
swallow tribe, it does not depend upon insects for its living, 
but take its prey from the water, after the manner of a 
gannet, striking the small fish that are near the surface with 
its bill. In taking their prey they often dive beneath the 
surface for a considerable depth. Stormy weather they 
appear to delight in, they then visit the shore, and I have 
repeatedly seen them miles from the sea coast on a rough 
windy day following the course of the Barwon River. 
The Spine-tailed Swift (Chá2tura caudacuta Lath.) This 
is one of the largest, if not the largest, of the Swallow tribe, 
measuring about 22 inches across the wings. 
The development of the muscles of the breast and wings 
is something immense for so small a bird, while the muscles 
of the legs are correspondingly weak, showing that the bird 
must depend upon its wings for its livelihood. The feathers. 
of the wings are so strongly set to the bone that it is only 
with great difficulty that they can be detached. The eye of 
