On the so-called Sterna Portlandica. 201 



XXII. — /Some Additional Light on the so-called Sterna 

 Portlandica, Ridgway. 



Br W)I. BRKWSTER. 

 Read Nov. 1, 1875. 



Shortly after Mr. Ridgway's article on this supposed 

 species appeared in the " American Naturalist," I published 

 a few additional notes on the same subject in the "American 

 Sportsman" (Jan. 16, 1&75). Having since been enabled by 

 the acquisition pi a fine series of terns to make some further 

 investigations into the matter, I am now not a little disposed 

 to question the specific validity of S. Portlandica, and trust in 

 the course of the present paper to show clearly its true posi- 

 tion. 



Among the terns before me are eight specimens collected 

 on Muskegat Island, Mass., between the respective dates of 

 July 1st and August 9th ; of these I will briefly describe the 

 most extreme example. 



In size and proportion of parts, similar to S. hirundo. Forehead, sides 

 of head, neck all around, throat and entire under parts, clear, pure white. 

 Mantle, rump, aud upper surface of tail, pale pearly blue. Occiput, crown, 

 and space around eye, sooty black. A dark, slaty, cubital bar on the 

 wings. Bill deep glossy black, tipped with pale yellow, and with but the 

 faintest possible suspicion of a reddish tinge at the base of the lower 

 mandible. Tarsi and feet black, also with a slight shade of reddishness, 

 perceptible however, only when the parts are exposed to the strongest 

 light. 



Of the remaining seven specimens five are precisely simi- 

 lar in every respect but one, namely, in the slightly increased 

 reddishness of the feet and tarsi. The seventh bird has the 

 tarsi dark red with a blackish cast, while at the base of the 

 otherwise perfectly black bill is a small but distinctly out- 

 lined area of brick red, confined almost entirely to the lower 

 mandible and encroaching but slightly upon the upper. In 



