18 ANATOMY 
A, Ambiens + 
a, Coeca + 
a. Aftershaft +¢.g. Gallinze, Impennes, Phcenicopterus, 
Musophaga, ete. 
f. Aftershaft — e.g. Anseres, ete. 
b. Caeca — 
a. Aftershaft+eg. Accipitres, Psittaci partim. 
B. Aftershaft — e.g. Columbze partim. 
B. Ambiens — 
a, Czeca + 
a. Aftershaft +e¢.g. Alca, Podicipes. 
f. Aftershaft — e.g. Striges. 
b. Cxca — 
a. Aftershaft +e.g. Psittaci pt., Cypseli, Trochili, etc. 
B. Aftershaft — eg. Passeres, Columbe pt., Herodii, ete. 
Thus the Owls in this arrangement approach nearest to the 
Auks and Grebes, while the Parrots, owing to their variable 
ambiens muscle, are grouped either with the Accipitres, or with the 
Swifts and Humming-birds. This is obviously unsatisfactory, per- 
haps owing to the value of the ambiens muscle being overrated. 
Let us next use the aftershaft as the principal, the ambiens as the 
secondary determining character, and the ceca as the third. Then 
the Psittaci approach the Gallinaceous birds and also the Auks and 
Grebes, while the Owls verge into the neighbourhood of Pigeons, 
Herons, and Passerine birds. Again, by using the ceca as the prin- 
cipal, and the ambiens as the secondary feature, Psittaci, Accipitres, 
and Columb, Owls, Auks, and Grebes are once more thrown to- 
gether. ‘The same or very similar arrangements result from a 
combination of the ceca with the oil-gland, or of the ambiens and 
ceca with the conditions of the palatal bones. But these per- 
sistent coincidences will never induce us to look upon them as 
indicating relationship between Owls, Auks, and Grebes, because 
this conclusion would be obviously wrong! How does the ques- 
tion stand with regard to other combinations, when we cannot at 
a glance discern a glaring error? When, ¢g. according to the 
muscles of the thigh, leaving out the ambiens, Striges, Accipitres, 
and Cypselide stand closely together? Is this a mere coincidence 
_ or does a deeper meaning underlie this Trias? It is obviously not 
due to a superior taxonomic value of Garrod’s myological formule, 
because application of the same principle throws Nightjars, Storks, 
and Parrots together. 
It is hopeless to attempt to arrive at a natural classification of 
Birds by a mechanical arrangement of even a great number of 
alleged leading characters. More may be expected from the com- 
bination of various taxonomic arrangements, each of which has 
been based upon a single organic system without reference to other 
