46 PROCEEDINGS OF THE ACADEMY OF 



Hydrochelidon fissipes. 



Migrant only ; very abundant. This tern differs somewhat 

 from the rest, in its times of migrating and other particulars. It 

 is not very common, comparativel}', in spring, and passes north 

 swiftly and silentl}^ The first spring I saw none until May 15th, 

 and had begun to think that I had missed them, or that they 

 ■ were migrating inland, when they became plenty, but only for a 

 week or ten days. All that I saw were in perfect spring dress. 

 They return in the van of all the terns, about the second week in 

 August, when many are still black, but bj' far the greater number 

 in the plumage of the j'oung. They remain until October — not 

 later, I think — and during September are as common as any of the 

 others. Although they flock with the rest over the harbor, and on 

 its sand-bars, they also frequent the marsh, where they flutter about 

 for hours, busy catching insects — chiefl}^ grasshoppers, I think — 

 in a manner that reminds one of night-hawks similarly engaged ; 

 and, in fact, the two birds are frequently associated together at 

 such times. 



Haliplana fuliginosa. 



Concerning this species I can offer nothing bej'ond the record 

 of the appearance of a flock Alarch 16, 1869, during a southwest 

 gale. I have seen none since, and can as little account for this 

 as for their isolated appearance on that occasion. If, as is most 

 probable, the gull-billed, arctic and roseate terns pass this point, 

 they escaped me altogether. 



Rhynchops nigra. 



These birds I have only noticed late in the summer, and during 

 the autumn, though I presume that they pass by in the spring '■> 

 none breed here, to my knowledge. In September they become 

 plentiful, and so continue until the latter part of November, some 

 doubtless remaining later. In examining large numbers of spe- 

 cimens, I find a great difference in size, and particularly in the bill. 

 Some individuals are fully a third heavier than others. The bill 

 varies over an inch in length, and especially in the length of the 

 under mandible. Sometimes the difference between the two man- 

 dibles is hardly a third of an inch; at others, over an inch. The 

 oblique striae on the under one are sometimes obsolete. In high 

 condition, the bill is bright red (vermilion) and black ; otherwise, 

 orange and black, or even mostly dusky, only yellowish at base. 



[May 9, 



