NATURAL SCIENCES OF PHILADELPHIA. 31 



The beach and marsh are cleared of all their sandpipers about 

 the first of June; and, for some six weeks, scarcely a straggler of 

 any sort is to be seen. But about the middle of July — a few 

 days before or after the 15th — a few of this and the next species 

 reappear, and in August the numbers are materially'' increased, 

 still in advance of the main body of September arrivals. It is 

 an open question about these July birds. It seems improbable 

 that they should have gone so far north as the most southern 

 places where we know of their breeding, and have raised a brood, 

 in the short six weeks of their disappearance. Probably they are 

 either those that left in the van of the spring migration, or those 

 that did not accomplish a complete migration, from whatever 

 cause. 



Ereunetes pusillas. 



Extremely abundant, as elsewhere along the Atlantic coast, 

 during the migrations ; here, chiefly from early April to June, 

 and from August (see above) through October. They show as 

 decided preference for the beach as the least sandpipers do for 

 muddy flats. 



Calidris arenaria. 



Very abundant at all times, excepting during the three summer 

 mouths. The greater number pass north early in May, but a few 

 linger until June. Some arrive late in August, and most of them 

 in September. After October they are conspicuous by their light 

 color, appearing almost white at a distance. The vernal change 

 commences in April, but the process is slow, and few completely 

 ruddy birds are seen here. Up to a short time before their de- 

 parture, they continue in compact flocks ; but in May, are more 

 dispersed, and the prospective pairs are seen chasing each other 

 over the sand, the males, pufied up to nearly twice their usual 

 size, going through a variety of odd motions, and piping in ex- 

 cited tones.^ 



' In this bird, with no external trace of a haUux, the accessory metatarsal is 

 present, without, however, bearing even a rudimentary phalanx, and without 

 causing any protuberance of the metatarsal envelope. It is a small oval or 

 somewhat reuiform ossicle, slightly twisted on itself, and deeply sulcate 

 along the middle, lying in the fossa between the three prongs of the meta- 

 tarse, where it is ligamentously bound down. It lacks the usual roughened 

 surface of opposition with the principal bone. Independently of morpholo- 

 I8n.] 



