2 9 
Sclater on the Sy sterna Avium. 
Sectio Tracheophonce. 
xix. Dendrocolaptidas. xxii. Tyrannidse. 
xx. Pteroptochidas. xxiii. Cotingidse. 
xxi. Formicariidae. xxiv. Phytotomidas. 
i. Momotidse. 
ii. Todidae. 
iii. Alcedinidae. 
iv. Galbulidae. 
v. Bucconidae. 
Ordo Fissirostres. 
vi. Trogonidse. 
vii. Caprimulgidae. 
viii. Cypselidas. 
ix. Trochilidae. 
Ordo S'CANSORES. 
i. Cuculidae. iv. Picidae. 
ii. Rhamphastidas. v. Psittacidae. 
iii. Capitonidae. 
This arrangement of the three first orders of birds I employed 
until 1872, allowing the Accipitres to succeed, and the remaining 
orders to follow, according to the Grayian system. But in 1872 
it was necessary to decide what arrangement should be employed 
for the remaining orders in the list of Neotropical birds (‘No- 
menclator Avium Neotropicalium’) which I was then preparing 
together with Mr. Salvin.* In the mean time the famous inves- 
tigations of Prof. Huxley on the bones of the palate in the class 
of birds had taken place, and an entirely new arrangement of the 
class, consequent upon these investigations, had been promul- 
gated. Having long entertained serious doubts as to the validity 
of the Grayian system, especially as to the groups associated to- 
gether in the orders Grallae and Anseres, I was pleased to find 
an alternative which had the sanction of high authority. Prof. 
Huxley had commenced his 44 System a with the lowest and 
most reptilian birds, and had ended it with the highest and most 
specialized. But it seemed to me that, by exactly reversing this 
arrangment, I should obtain a scheme which would not very far 
deviate from that which I had already employed as to the first 
three orders, and would offer many improvements on the Grayian 
system in the remainder. In the introduction to the 4 Nomencla- 
tor,’ accordingly, I gave the subjoined scheme as that which I 
proposed to employ for the general arrangement of living birds, 
dividing them into 21 orders, as follows .: — 
* [The arrangement adopted in the ‘ Nomenclator ’ is entirely Mr. Sclater’s. I was 
forced to desert my colleague when I visited Central America in 1873-4, a portion only 
of this work having been then printed hnd the Introduction unwritten. O. S.] 
t P.Z.S. 1867, p.456 
