Sentence:  Both the Cuckoos and the Moth-hunters pertain to that extensive order of birds which, in an arrangement of the class which I had lately the honour of submitting to the Zoological Society, I designated Strepitores, (or <WSD>Screechers</WSD>); an order characterized by numerous physiological agreements, but which embraces many forms externally dissimilar—that is to say, in those adaptive characters which have reference to a special mode of life. It is only in this group, among what have been termed perching birds, that the vocal organ is simple, or furnished with only a single pair of muscles; in consequence of which its various members are unable to inflect the voice 
Meaning of the word marked with <WSD> tags:  A bird of the former category (order), distinguished from the songbirds. (en)