BIRDS OF THE CAMBRIDGE REGION. 9 



Concord River Valley than with the region to the eastward. For similar 

 reasons it has seemed undesirable to take in more than the extreme western 

 borders of Medford and the southern portions of Winchester, while the greater 

 part of Somerville has been disregarded because it is too thickly settled to pos- 

 sess any ornithological interest. The total area included is definitely bounded 

 on the south by Charles River, on the southwest and west by Stony Brook and 

 its principal tributary, Hobbs Brook. Beyond Hobbs Brook Reservoir the line 

 follows the western border of Lexington northward, and the northern borders of 

 that town and of Arlington southeastward and eastward to the Upper Mystic 

 Pond. After curving around the northern end of this pond, where it takes in a 

 small part of Winchester, the line runs nearly straight in a generally southeast- 

 erly direction through the western portions of Medford and Somerville to Craigie 

 Bridge, its starting point on Charles River. 



No land bird not definitely known nor credibly believed to have been found 

 within the boundaries just named, has been given a numbered place in the list. 

 With the waders and water-fowl, however, the ruling has been somewhat less 

 strict. They are notoriously addicted to flying back and forth over their entire 

 feeding grounds, especially just before alighting, and for this reason both sides 

 of Charles River and the Back Bay Basin, with the bordering marshes, are con- 

 sidered, in relation to these birds, as coming within the legitimate scope of the 

 present paper. 



Of the physical characteristics of the Cambridge Region it may be well to 

 say a few general, preliminary words in this connection. The region comprises 

 roughly about fifty square miles. Its extreme eastern portions, situated between 

 the Charles and Mystic Rivers in Cambridge and Somerville, and in the eastern 

 parts of Belmont and Arlington, are for the most part nearly level and but 

 slightly elevated above tide-water. This low-lying plain, most of which is now 

 densely populated, is enclosed on every side by hills, and crossed from north to 

 south by a chain of fresh-water ponds of which the most noteworthy are the 

 Upper and the Lower Mystic, Spy, Little, Pout, Fresh, and Bird's Ponds. To 

 the westward the land rises rather gradually in the neighborhood of Mount 

 Auburn and Fresh Pond, but very abruptly between the town centers of Arling- 

 ton and Belmont where the plain is terminated by a wall-like ridge elevated in 

 places to above three hundred feet and stretching northeast and southwest for 

 a distance of two or three miles. Beyond this the country is thinly settled, 

 extensively wooded, and everywhere broken and hilly. The principal elevations 

 are Prospect Hill, Waltham (482 ft.). Bear Hill, Waltham (360 ft.), Arlington 

 Heights, Arlington (380 ft.), Loring Hill, Lexington (360 ft.), and Wellington 

 Hill, Belmont (310 ft.). Although well watered by brooks (most of which flow 

 into either the Charles or the Mystic), the western portions of the Cambridge 



