486 A CONTRIBUTION TOWARDS OUR KNOWLEDGE OF 



A. colli laterale. This divides the lower half of the pt. colli into dorsal and 

 ventral moieties (p. 484') ; it is a forward continuation of the 



A. triuici laterale. The area of the space is much restricted by reason of the 

 great extension of the hinder portion of the pt. spinalis. It extends downwards and 

 backwards, so as to divide the pt. ventralis from the pt. cruralis, and is continued 

 forwards to the point where the pt. humeralis forms the pt. ventralis. Passing upwards, 

 above the wing and humeral tract, it becomes the Apt. colli laterale. 



A. mesogastroei. This lies in the mid-ventral line and extends from the cloacal 

 aperture forwards to about the middle of the neck. 



III. The NestliiNG Plumage. 



Dr Gadow (5) coined the word Neossoptiles, to distinguish the plumage of 

 the nestling birds — when present — from the Teleoptiles or plumage of the adult. 

 Later, I showed that this nestling plumage was often made up of two different kinds 

 of down. The one preceding definitive down feathers, the other preceding definitive 

 contour feathers. For the former I proposed the term pre-plumulse, and for the latter 

 pre-pennse. Sometimes, as in the Duck, the nestling plumage consists of pre-penn£e 

 only, sometimes, as in the case of the young Hawk, of both kinds. 



The nestling Megapode possesses no pre-plumulfe, and it is doubtful whether 

 pre-pennse, in the sense in which this word was originally used, occur. It seems 

 certain that the pre-penna3 representing the remiges and contour feathers generally 

 are shed during embryonic life (see p. 488). If this proves to be true, and there 

 seems to be room for but little doubt, we have a third form of nestling plumage — 

 a stage between the pre-penna proper, and the actual definitive feather of the adiilt. 

 In passing we might remark that this is unique only in so far as the time of its 

 appearance is concerned; for, as the wTiter has already pointed out (11), the young 

 Owl dons a special, woolly form of covering intermediate between the pre-pennse and 

 the definitive feathers, whilst, as already remarked, the pre-peima? of the Megapode are 

 lost in embryonic life, so that the young Megapode starts life in the same kind of 

 plumage as that assumed by the young Owl later on. The structure of this nestling 

 plumage is discussed on p. 488. 



It is sufficient to remark here, that the nestling has no rectrices, and that 

 the development of the first cubital remex, as in the nestling chick, is arrested ; 

 its place being filled by a few downy filaments — probably representing a true neos- 

 soptile. The remex probably does not appear until after the first moult of the 

 " quilLs." The wing further agrees with that of the Common Fowl, and of 

 Opisthocomus — in that the development of the outer primaries is suppressed until 

 later in life. I have discussed the significance of this in recent papers (8, 10). It 

 is probable that in the case of the Megapode they do not, like the first cubital, 

 appear until after the first moult. In the nestling Megapode and Opisthocomus there 

 are 8 primaries, in the adult 10. In the nestling Chick there are 7 primaries, in the 



