252 
Birds of Celebes: Meropidae. 
be a valid subspecies, there is strong reason to suppose that it will be found 
to make its way to Australia by a ditferent route from that of the great body 
Avhich crosses Torres Straits in September and February. We suspect that all 
the birds of the Lesser Sunda Islands — Bali to Timor — may be identified with 
M. ornatus sumhaensis and that they make their way in due season by way of 
iimor and Botti to Australia across the Timor Sea, which is not without 
a few small islands and reefs to serve as resting places. 
As in Prioniturus, the bare shafts of the lengthened middle tail-feathers of 
adults are not the result of the wear and tear undergone by these feathers 
between the yearly or half-yearly moult of the species. But it is obvious that 
the webs of the feathers, and, especially, of the two long central tail-feathers, 
must get damaged and worn down considerably in a bird which burrows a sort 
of mouse-hole a yard deep in sand; the tail-feathers in particular will he rubbed 
and bent about, when the bird turns round in its nesting cavity at the end of 
its hole. In two or three specimens before us (C 2224, Nr. 13590, C 12205), 
the spatules seem to have suffered from this cause. In adult specimens, however, 
the spatules grow out of the shaft perfectly formed; the above men- 
tioned specimen, C 2224, with one old spatule of 72 mm is getting a new one, 
the bare shaft of which is 30 mm long, while about 10 mm more of bare shaft 
at the base is still enclosed in the sheath out of which it is growing (see 
Plate VIII). In birds of the year the tail is square and simple, and it appears 
that in young specimens of the second year, as in Prioniturus, the middle tail- 
feathers are not greatly longer than the lateral ones, and the projecting part is 
usually not bare of web, but simply much narrowed and hollowed out a little 
behind the tip. Those with very long bare spatules are without doubt older birds. 
The case of the Bee-eaters, like that of Prioniturus, where we have discussed 
the matter more fully, appears to be a remarkable illustration of the inheri- 
tance of mutilations, an effect of wear and tear, continually repeated throughout 
countless generations, being ultimately reproduced in the offspring, the successive 
ontogenetic changes in which betray the gradual result wrought by the attrition 
of the sand on its more remote, and less remote, ancestors^) . 
1) It is very possible that the peculiar heart-shaped double tips of the secondaries and of all the pri- 
maries (except the longest) owe their formation to the same cause. Has Mero'ps the habit of supporting itself 
on its opened wings when it clings to the steep sand-bank in which it commences to dig its nest? Mr. Bruno 
Gleisler, who observed Merops breeding in a river-bank in Java informs us that this is the case. House 
and Sand Martins also do so and it is of special interest to observe that the same curious quill-formation 
obtains in them as well. If our supposition is correct, the pressure on the feathers and the oscillation of the 
body of the pecking bird will force the ends of the webs apart from the shaft on one or both sides of it, 
forming a little notch, just as is seen if the tip of a perfect quill be tapped gently with the finger or rubbed 
on blotting paper or other rough substance. It is important to observe that the double-tips of the quills in 
Merops and other birds are arranged in what Mr. Keeler would term “Successional Taxolbgy”: — in the 
inner secondaries the outer web of the feathers has the shorter tip, in the middle of the wing the tips are 
about equal, in the outer secondaries and primaries the inner web has the shorter tip; in other words, where 
one tip is more exposed to friction than the other, it is shorter; where they are equally 
exposed, they are equal Moreover, in the middle of the wing the secondaries have a very square appear- 
ance, as if they had been truncated by some means. We conceive that the wings of Merops ai’e much less 
