12 NORTH AilERICAN BIRDS. 



wing, 4.20; tail, 3.10, — total, about 7.50. Some .specimens slightly exceed 

 these dimensions ; few, if any, fall short of tiiem. 



In autumn the upper surface is somewhat different from that in spring, 

 being less grayish, and with a tinge of rich sepia or suutf-bro^vu, this 

 becoming gradually more ajipreciable ou the tail. 



A specimen from Costa liica is uudistiuguishable from typical examples 

 from the Eastern United States. 



Habits. Tliis species, first described in the ninth volume of the Pacific 

 Eailroad Surveys, bears so strong a resemblance to the Olive-backed Thrush 

 {T. miMinsoni), that its value as a species has often been disputed. It was 

 fii'st met with in Illinois. Since then numerous specimens have been ob- 

 tained from the District of Columbia, from Labrador, and the lower 

 ]\Iackenzie Eiver. In the latter regions it was found breeding abundantly. 

 It was also found in large numbers ou the Anderson Eiver, but was rare 

 ou tiie Yukon, as well as at Great Slave Lake, occurring there only as a 

 bird of passage to or from more northern breediug-gi-ounds. 



In regard to its general habits Init little is known. Dr. Coues, who 

 found it in Labrador, breeding abundantly, speaks of meeting with a family 

 of these birds in a dee]) and thickly wooded ravine. The young were just 

 about to fly. The parents evinced tlie greatest anxiety for the safety of 

 their brood, endeavoring to lead him from their vicinity by Muttering i'rom 

 bush to bush, constantly uttering a melancholy 'plievgli, in low whistling 

 tone. He mentions that all he saw uttered precisely the .same note, and 

 were very timid, darting iuto the most impenetrable thickets. 



This thrush is a regular visitant to Massachusetts, both in its spring iind 

 'vl\ its fall migration. It arrives from about the first to the middle of j\Iay, 

 and apparently remains about a week. It passes south about the first of 

 October. Occasionally it appears and is present in Massachusetts at the 

 same time with the Turdiis swainsoni. From this species I hold it to be 

 unquestionably distinct, and in this opinion I am confirmed by the observa- 

 tions of two very careful and reliaUe ornithologists, ^Ir. William Brewster 

 of Cambi'idge, one of our n)ost piomising young naturalists, and Mr. George 

 0. Welch of Lynn, whose experience and observations in the field are 

 unsurjMissed. They inform me that there are observable between these 

 two forms certain well-marked and constant differences, that never fail 

 to indicate their distinctness with even greater precision than the constant 

 though less marked diiferences in their plumage. 



The Turdus cdicice comes a few days the earlier, and is often in full song 

 when the T. swainsoni is silent. The song of the former is not only 

 totally different from that of the latter, but also from that of all our 

 other Wood Thrushes. It most resembles the song of T. pallasi, but 

 differs in being its exact inverse, for whereas the latter begijis with its 

 lowest notes and proceeds on an ascending scale, the former begins with 

 its highest, and concludes with its lowest note. The song of the T. swain- 



