,656 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



List of sjpecimeiis. 



HYDEOCHELIUON LAEIFORMIS, {Limi.) Coues. 



Black Teen. 



This, the ooly representative of the Sternmw observed by the Com- 

 mission, was found breeding at Pembina in June, and subsequently 

 seen during August along the Mouse Eiver. On one of the prairie 

 sloughs at Pembina — the some that I have spoken of as the breeding 

 resort of the Yellow-headed Blackbirds — a colony of perhaps twenty 

 pairs was established. As usual during the breeding- season with 

 Terns, the birds were very fearless when their nesting-place was in- 

 vaded, and I regret to say that the colony was broken up in conse- 

 quence, as I desired to secure a good series of specimens in full dress. 

 Ko eggs were found until the latter part of the month. It required 

 sharp scrutiny to discover them, as they lay, without any preparation 

 for their reception, directly upon the soaking, matted masses of last 

 year's reeds, and were closely assimilated in color. They were indiffer- 

 ently two or three in number, oftener the latter ; average samples 

 measured 1.35 in length by 0.95 in breadth. The coloration is not 

 peculiar in comparison with that of other Terns' eggs. 



List of specimens. 



