370 The American Naturalist. [April 
is comforting to find that there are now, among scientific men of dis- 
tinction, champions of the belief of my boyhood days that a swift is 
merely a peculiar kind of swallow.” 
Now as to my “strange hallucination” in the matter of Professor 
Huxley’s views upon the classification of the Swifts, Swallows, and 
Humming-birds. I have a well-worn copy of his famous P. Z. 8. 
memoir of 1867—one of the most remarkable contributions ever 
written upon the classification of birds—and, I may add, a perfect 
monumental beacon, warning comparative avian anatomists for all time 
in their attempts to classify birds, against trusting to any single set of 
characters. In his “Cypselomorphe” Huxley placed only the Swifts, 
Humming-birds and Goatsuckers (pp. 468, 469). It was done upon 
only too few characters, and mainly based upon the osteological ones 
seen at the base of the skull. But Huxley believed the vomer of a 
Humming-bird was “ truncated at the anterior end,” an error which 
both Parker and myself independently pointed out for him. But a 
quarter of a century is a long time in comparative anatomy (1867- 
1892), and if Professor Huxley has kept up with the literature of the 
subject he may hold entirely different views at the present writing. 
This would appear to be the more probable, as his misgivings were 
sufficiently strong as to have him write in his 1867 memoir that “In 
their cranial characters the Swifts are far more closely allied with the 
Swallows than with any of the Desmognathous birds, the Swift pre- 
senting but a very slight modification of the true Passerine type exhib- 
ited by the Swallow (Joe. cit. p. 456). May I ask Mr. Ridgway what 
he thinks Professor Huxley meant when he wrote that sentence? 
And does he believe that to-day Professor Huxley would retain the 
Caprimulgi with the Humming-birds and Swifts together in one group 
and consider it to be a natural one? 
One word more and I have done for the present. In the case of 
doubtful affinity among birds, as with all other forms, there is but one 
true way of getting at a solution, and that is to critically weigh and 
compare everything that is known about the one group with evergthing 
that is known about the other, before finally deciding. Now I chal- 
lenge Mr. Ridgway to take any species of North American Humming- _ 
bird and any species of North American Swift, and arrange in two 
columns in a comparative way all that is known about either species, 
paleontologically, biologically, morphologically, or otherwise, and then 
upon summing up give any real reason why the Trochili and the Cypseli 
should be considered to constitute by themselves a natural group of 
birds. I have very serious doubts as to his ability to do this. If he 
