498 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
instance was so striking that I could not help noticing it, and since 
then, having been on the alert for similar cases, I have verified my 
experience. 
Family SYLVUID. 
The warblers need only a passing reference, as, owing to their dull 
coloration and small size, they can all be said to more or less possess 
protective resemblance, and it would therefore be idle to attempt to 
give a list of those species endowed with it. I am well acquainted 
with the habits of many of the species, and have often noticed how 
inconspicuous they are when sitting among the grass or bushes of 
their usual haunts. They are, moreover, for the-most part of retiring 
habits. 
Order Picart™. 
Family CAPRIMULGID. 
The members of this family are on the whole very well endowed 
with assimilative coloration. I have noticed this fact in regard to 
the European nightjar (Caprimulgus europeus). Crouching on the 
ground it is a most inconspicuous object, even on brightly moonlight 
nights. I first became acquainted with the case of the rufous-cheeked 
nightjar (C. rufigena) on September 27, 1898. During a collecting 
excursion to a farm about 5 miles southwest of Kaalfontein station 
I happened to be resting under a tree. Staring aimlessly up into 
the foilage overhead, my gaze was arrested by an irregular bump 
or protuberance on a bough about 12 feet above my head. I could 
not make out what it was, so, thinking it might be a nest of some sort, 
I ascended the tree and was considerably astonished to find a nightjar 
fiy up from almost under my nose. The bird had been sitting 
lengthways on the bough, flattened up against it, and the assimilative 
nature of its plumage was most marked, the mottled gray-brown and 
rufous feathering harmonizing beautifully with the bark of the tree 
on which the nightjar sat. I followed the bird with my eyes as it flew 
up, and descending to the ground I proceeded to the tree it had taken 
refuge in, but was forced to study every branch before I located it 
again. Being mostly nocturnal in habits, a protectively colored 
plumage would naturally be of very material assistance to them when 
in hiding during daylight in some recess or on a bough. Since this 
occasion I have repeatedly verified this experience, as this bird is 
fairly common in the Modderfontein district. In the neighborhood 
of Grahamstown I also noticed this fact with reference to C. 
pectoralis, which seems to be the commonest species of the bush 
region. My friend, Mr. Robert Ivy, has also repeatedly noted the 
remarkable assimilative coloration of this bird, and photographed a 
