The nests of this bird, so far as I have seen them, are all flat, shallow structures, with very slight depression, and loosely and rudely constructed of an intermingling of strips of bark with rootlets and the finer stems of herbaceous plants. Their eggs, usually four in number, do not vary essentially in size, shape, or marking. They measure 1 inch in length, and from .73 to .75 in breadth. Their ground color is a bright greenish-blue, marked with deep olive-brown spots, intermingled with blotches of a light lilac. There are slight variations in the proportion of green in the shade of the ground color, and also in the number and size of the spots, but these variations are unimportant. The following are Mr. Ridgway’s observations upon the habits of this species. They are full, valuable, and very carefully made:— The _Oreoscoptes montanus_ is a bird peculiar to the artemisia wastes of the Great Basin, being a characteristic species of the region between the Sierra Nevada and the Rocky Mountains. It is exclusively an inhabitant of the “sage brush,” and is partial to the lower portions of the country, though it is not unfrequent on the open slope of the mountains. A more unappropriate term than “Mountain Mocking-Bird” could hardly have been chosen for this species, as its predilection for the valleys, and the fact that its song is _entirely_ its own, will show. In my opinion, the term “Sage Thrasher” would be more appropriate. In the neighborhood of Carson City, Nevada, these birds arrived about the 24th of March, and immediately upon their arrival began singing. At this time, with the _Sturnella neglecta_ and _Poospiza belli_, they made sweet music in the afternoon and early morning, in the open wastes of “sage brush,” around the city. The birds when singing were generally seen sitting upon the summit of a “sage” bush, faintly warbling, in the course of the song turning the head from side to side in a watchful manner. Upon being approached, they would dart downward, seemingly diving into the bush upon which they had perched, but upon a close search the bird could not be found, until it was heard again singing a hundred yards or more in the direction from which I had approached. This peculiar, circuitous, concealed flight is a very characteristic trait of this bird, and one sure to excite attention. As the season advanced, or about the 10th of April, when the pairing season was at hand, the songs of the males became greatly improved, increasing in sweetness and vivacity, and full of rapturous emotion; their manners, also, became changed, for they had lost all their wariness. In paying their attentions to their mates, the males would fly from bush to bush, with a peculiar, tremulous fluttering of the wings, which, when the bird alighted, were raised above the back apparently touching each other; all the while vibrating with the emotion and ecstasy that agitated the singer.