630 NIDIFICA TION 
all being birds that breed in holes, as Alcedines, Bucerotidx, Coracude, 
Cuculidx, Cypseli, Meropide, Momotidx, Musophagidx, Pici, Todide, 
Trochilide. 
The Bucconidx, Coliidx, Eurylemidx, Galbulide and Trogonidx are 
probably all naked. 
Menura is said to have downy nestlings. 
Opisthocomus is born with open eyes, but is fed by its parents, 
and has an imperfect nestling plumage. 
The interesting correlation between Neossoptiles and permanent 
Downs (see FEATHERS, p. 242) is shewn (T'hter-reich, Vogel, Systemat. 
Theil, pp. 76:85). 
NIDIFICATION, or the building of the nest in which the Eccs 
are to be incubated and hatched, is with most Birds the beginning of 
the real work of the breeding-season, to which SONG and its con- 
comitant actions are but the prelude or the accompaniment; but 
with many it is a labour that is sceamped if not shirked. Some of the 
AUK tribe place their single egg on a bare ledge of rock, where its 
peculiar conical shape is but a precarious safeguard when rocked by 
the wind or stirred by the thronging crowd of its parents’ fellows. 
The Stone-CURLEW and the NicHTJAR deposit their eggs without the — 
slightest preparation of the soil on which they rest; yet this is not 
done at haphazard, for no birds can be more constant in selecting, 
almost to an inch, the very same spot which year after year they 
choose for their procreant cradle! In marked contrast to such 
artless care stand the wonderful structures which others build for 
the comfort or safety of their young. But every variety of dis- 
position may be found in the Class. The Apteryx (Kiw1) seems to 
entrust its abnormally big egg to an excavation among the roots of 
a tree-fern ; while a band of female OSTRICHES scrape holes in the 
desert-sand, and therein promiscuously dropping their eggs cover 
them with earth, and leave the task of incubation to the male, who 
discharges the duty thus imposed upon him by night only, and 
trusts by day to the sun’s rays for keeping up the needful, fostering 
warmth. Some MEGAPODES bury their eggs in sand, leaving them, 
as many Reptiles do, to come to maturity by the mere warmth of the 
ground, while others raise a huge hotbed of dead leaves wherein they 
deposit theirs; but in either case the young are hatched without 
further care on the part of either parent. The GREBES and some 
RAILS seem to avail themselves in a less degree of the heat generated 
by vegetable decay (b. Norf. iii. p. 240),? and dragging from the 
bottom or sides of the waters they frequent fragments of aquatic 
1] make this statement literally on the experience of my brother Edward 
and myself, but I believe it will be abundantly confirmed by the evidence of other 
observers. 
2 Mr. Southwell found the temperature of an unincubated nest of Podicipes 
cristatus to be 67°, that of two incubated nests to be 72° and 73° respectively, 
