2 Proceedings of the Biological Society of Washington. 



Washington was given as 293, ^ of which 2 are hybrids. The 

 present hst comprises 299 species and subspecies, besides 2 

 hybrids and 2 hypothetical forms. Five of the additional 

 forms — Glaucous Gull, Red-legged Black Duck, White-rumped 

 Sandpiper, Black-bellied Plover, and European Starling — have 

 been detected in the vicinity since the publication of Professor 

 Cooke's papers; the others are included on the basis of old 

 records which have recently come to Hght. It is probable that 

 before long some of the more recently described subspecies 

 known to migrate through the eastern United States will be 

 added to the Washington list. One species, Barrow's Golden- 

 eye, which was included by Professor Cooke as doubtful, is here 

 omitted since reexamination of the specimen has shown it to be 

 the American Goldeneye. One species, the Sooty Shearwater, 

 has been transferred to the hypothetical list because of insuflfi- 

 cient data. 



The territory covered in the present paper is approximately 

 that within a radius of about twenty miles from the Capitol, 

 including Sandy Spring, Laurel, Camp Meade, Upper Marl- 

 boro, and Marshall Hall, Maryland, and Mount Vernon, Fair- 

 fax, and Great Falls, Virginia. This is a slight extension of the 

 limits nominally used in previous lists. 



In the following table of migration dates, the figures under the 

 heading "No. of dates" indicate the number of dates of arrival 

 or departure used in calculating the succeeding average dates. 

 Since the object of migration averages is to indicate the normal 

 date of arrival or departure, certain exceptionally early or late 

 dates of occurrence have been recorded as "accidental" and not 

 used in figuring the averages. In the case of spring arrival, 

 dates that are late enough unduly to affect the average have 

 been discarded as not representing first arrivals. In the 

 computation of averages, when the result includes a fraction of 

 less than one-half, the next lower whole number has been used; 

 and in the case of a fraction of more than one-half, the next 

 higher whole number has been used. 



The species known to occur in this region are classified under 

 four heads: (l)Permanent Residents, those which are found in 

 the region at all times of year; (2) Regular Migrants, migratory 



iThis was due to an error in counting. The actual number of names in the 1908 list 

 is 294- 



