EGGS 189 
In regard to the almost countless cases of spotted eggs in holes 
or covered nests, of which so many groups of birds furnish 
examples either wholly or in part, the only supposition that could 
apparently justify the last statement would be that the species 
in question have taken to hiding their treasures in times compara- 
tively recent, and have not yet got rid of the ancestral habit of 
secreting and depositing pigment. In support of such an argument 
might be alleged, among some other cases, the generally pale colour- 
ing of eggs of the Daw, Corvus monedula, compared with those of its 
kindred, as indicating a step in this direction, while a more con- 
clusiveone has been taken by those members of the Hirundinidz as the 
Sand-Martin, Cotile riparia, and House-Martin, Chelidon urbica, which 
breed in holes or build close nests—their relative the Swallow, 
Hirundo rustica, though its nest is rarely exposed to direct light, con- 
tinuing to lay eggs that are conspicuously spotted with two or three 
tints. But if this supposition be valid some other one, on (it would 
seem) a wholly different principle, must be found to explain why 
perhaps the eggs that are at once the most delicately and most 
richly coloured laid by any bird are those of the Snow-BuUNTING, 
Plectrophanes nivalis, which except in rare instances are so sedu- 
lously concealed as to be almost beyond the reach of reflected light ; 
and again, why the several species of NuTHATCH, Sitta, which must 
have been ages in learning the art of masonry they so skilfully 
practise, lay eggs more deeply dyed than those of their felt-making 
brethren the Paridz (Tirmousk), or their feather-bed cousins the 
WRENS and the TREECREEPERS. But the supposition would seem 
to break down wholly as an explanation of the variable colouring 
offered by eggs of the Fantail-WARBLER, Cisticola cursitans or scheni- 
cola—whether the observations of M. Lunel (Bull. Soc. Ornithol. Suisse, 
1865, pp. 9-30, pl. 7), referring the marvellous differences they 
present to the season of the year at which they were laid, be correct 
or not, for the ark-like structure of the nest remains constant. No 
more can here be added on this matter, interesting as it is, and 
worthy of much more investigation than it has received. 
The grain of the egg-shell offers characters that deserve far 
more consideration than they have received until the attention of 
Herr von Nathusius having been directed to the subject by some 
1 Having introduced Hewitson’s name in this connexion, and having pre- 
sently to refer to him again, I may say at once that his remarks on the color- 
ation of eggs, and some other subjects, have been frequently repeated, of course 
with more or less modification and verbose addition, by various plagiarists who 
have sometimes forgotten to mention the source of their information. With the 
greatest regard for my old friend, I am bound to say that the principles on which 
he wrote, more than fifty years since, are such as no man of science can accept 
now ; but they were those of his time, and the more recent adaptors of them are 
behind theirs. 
