Throughout I have retained the original language and spelling, except that I have replaced f’s with s’s (e.g., I have changed the spelling "fkin" to "skin" in the first sentence) to improve readability.

This is the entire Mute Swan account (from pp 543-4):

D. With a deep red bill, and black incurvated nail at the end: a triangular naked black skin between the bill and the eyes: at the base of the upper mandible a large black rounded protuberance; legs black: whole plumage of a snowy whiteness. WEIGHT sometimes twenty-five pounds.

PLACE. The Mute Swan, or that which we call Tame, is found in a wild state in some parts of Russia; but far more plentiful in Sibiria. It arrives, in summer, later from the south, and does not spread so far north*. Those which frequent the provinces of Ghilan and Mafenderan, on the south of the Caspian Sea, grow to a vast size, and are esteemed great delicacies. The Mahometans hold them in high veneration†

*Doctor Pallas

†Extracts, iii. 78."

Other quotes from the Whistling Swan account in the same book:

p. 541. "Those of the eastern parts of Sibiria retire beyond Kamtfchatka, either to the coasts of Armenia, or to the isles of Japan."

p. 542. "This species has several distinctions from the species which we, in England, call the Tame Swan. In Russia this species more fitly clames the name, it being the kind most commonly tamed in that empire. The Whistling Swan carries its neck quite erect: the other swims with it arched. This is far inferior in size. This has twelve ribs on a side; the MUTE^‡ only eleven. But the most remarkable is the strange figure of the windpipe, which falls into the chest, then turns back like a trumpet, and afterwards makes a second bend to join the lungs. Thus it is enabled to utter a loud and shrill note. The other Swan, on the contrary, is the most silent of birds; it can do nothing more than hiss, which it does on receiving any provocation.