The large species represented in our present plate is a native of Mexico and California, and lives exclusively in localities remote from the habitations of man. Though known as a bird of Mexico, it is not represented as an abundant species in that country, and within the limits of the United States has been observed only by Dr. Heermann, and Dr. Kennerly. In his notes on the Birds of California, in the Journal of the Philadelphia Academy, II. p. 263, Dr. Heermann’s observations on the present bird are as follows, and contain the first notice of this species as an inhabitant of the United States: “I first met with this bird in the fall of 1851, on the Consumnes river, but in the spring of 1852, I procured three specimens on the Calaveras river. It is an active bird, having a loud sprightly song, that is heard at a considerable distance, and which it repeats at short intervals. I found it occupied in searching for insects between and under the large boulders of rock which, along some portions of this river, are thrown together in confused masses, as if by some terrific convulsion of nature.” Dr. Kennerly, during the survey recently completed by Lieut. Whipple’s party, noticed this Wren in New Mexico, and obtained specimens now deposited in the National Museum at Washington city. For our present article he has very kindly favored us with the following note: “This active little bird was observed only among the hills along the head waters of Bill Williams’ fork. In the most rugged and inaccessible places it was generally found busily engaged in searching for food, rapidly passing around and among the rocks with great activity, and accompanying its movements with its short and peculiar chirp. It is so constantly in motion that specimens can only be obtained with difficulty.” This species was described by Mr. Swainson, from specimens sent to Europe from Real del Monte, in Mexico, and we have seen others from various parts of that country. The figure in the plate now before the reader, is that of an adult male, and is about two-thirds of the size of life. The plant represented is _Nemophila insignis_, a native of California. DESCRIPTION AND TECHNICAL OBSERVATIONS. Genus Troglodytes. Vieill, Nouv. Dict., XXXIV. p. 505. (1819.) Troglodytes mexicanus. (Swainson.) Thryothorus mexicanus. Swainson, Zool. Ill., 2d series, I. p. (none), pl. 11. Form. Bill, long, slender and curved; wings, short, rounded, with the fourth and fifth quills longest; tail, rather long; legs and feet, moderately strong; claws, large. Dimensions. Total length (of skin) about 5½ inches; wing, 2½; tail, 2 inches.