46 PROCEEDINGS OE THE ACADEMY OP 



Hydrochelidou fissipes. 



Migrant only ; xevy abundant. This tern differs somewhat 

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

 is not ver}' common, comparative!}^, in spring, and passes north 

 swiftly and silentl}'. The lirst 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 ai-e still black, but by far the greater number 

 in the plumage of the young. 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 frequentlj' associated together at 

 such times. 



Haliplana fuliginosa. 



Concerning tliis species I can offer nothing beyond the record 

 of the appearance of a flock 3Iarch 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, 

 the}^ 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 Septemlier the}' become 

 plentiful, and so continue until the latter part of NoA^ember, 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 striai 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, 



