Page 254. 
234 THE ANATOMY OF THE COLUMBZ. 
ance in all other birds, would lead me to consider their presence or 
absence as more significant than that of the oil-gland. 
In my last communication to this Society* I gave reasons to show 
that the presence or absence of the ambiens muscle was a very signi- 
ficant fact in the classification of birds generally. This would lead me 
to lay considerable stress on the same point in any order or suborder 
in which it is found to vary. 
Assuming then, as in my last paper, for reasons there stated, that 
the ancestral Pigeon possessed the ambiens muscle, and, on the same 
grounds, that it had ceca coli and an oil-gland, it is evident that the 
Pteroclide, together with Columba, Turtur, Macropygia, and Hctopistes 
have departed least from the ancestral type. The Pteroclidw have 
branched off in another direction, as will be subsequently shown; and 
therefore Columba, Turtur, Ectopistes, and Macropygia (together with 
those undissected genera unmistakably allied to them) may be con- 
sidered to be the least modified, and therefore most typical of the 
Columbee. 
From these, if the peculiarities of the ambiens muscle have the 
importance which I assign them, a branch sprang, in which the 
ambiens was undeveloped.. This includes at the present day Star- 
nenas, Phlogenas, Geopelia, Ptilopus, Treron, and Goura, most of which 
possess 14 rectrices, and are confined to the Malay archipelago. This 
Treronine division, as it may be termed, seems to be preserved in its 
primitive form in Phlogenas, in which no further structures are lost. 
Starneenas, which, notwithstanding its peculiar distribution, must be 
considered as a member of it, loses the oil-gland, and Geopelia, as 
well as Ptilopus, the ceca, whilst Teron and Gowra are deficient in both. 
The main stem seems to have shortly given off a second branch, 
in which the ceca coli were alone wanting. This Phapine branch is 
now represented, without further complication, by Calawnas, Carpo- 
phaga, Chalcopelia, Chalcophaps, Chameepelia, Leptoptila, Leucosarcia, 
Metriopelia, Ocyphaps, Phaps, Tympanistria, and Zenaida; whilst from 
it has sprung Diduneulus, without any oil-gland and with its quaint 
beak and remarkably long intestinal canal, which would indicate that 
its diet was usually one of fish, or more probably mollusca.t 
Respecting Lopholeemus, it may be mentioned that the only oppor- 
tunity I have had of dissecting it has been through the kindness of 
Mr. Edward Gerrard, who lent me two specimens, not well preserved, 
in spirit.t In these I could not find the least trace of the accessory 
* “ Proceedings of the Zoological Society,” 1874, p. 111. (Supra, p. 208.) 
+ It is through the kindness of Prof. Newton that I haye had the opportunity 
of dissecting a specimen of this rare bird. 
{ An additional specimen has come into my hands since the above was written, 
by which the accuracy of my previous dissections of the species is confirmed. No 
