NATATORES. 



403 



it walks in the same awkward position, frequently being obliged to 

 balance itself with its wings. With a more powerful exertion of its 

 wings, however, it was enabled to run along on its toes, in the same 

 manner that it does over the surface of the water. The absence of a 

 hind toe, the nails being but slightly bent and fiat, and, perhaps I may 

 add, its evidently being unaccustomed to this description of locomotion, 

 seemed to be the causes of its helplessness on its feet. 



" These birds have been numerous about us for some days past, and 

 their coursing over the water with flitting wings reminds me of the 

 actions of butterflies about a pool. One of them was seen swimming, 

 or at least resting, on the surface. We have seen this species very 

 frequently, indeed almost daily, since leaving America, and scarcely 

 any other sea-birds, except in the immediate vicinity of the islands. 

 It would seem that it scarcely ever visits the land, except for the 

 purposes of incubation, and there can hardly be a better comment on 

 its untiring power of wing than the popular fable amongst seamen, 

 that it carries its egg and hatches its young while sitting in the water. 

 It does not sail in the continued manner of the gulls and some other 

 sea-birds, but moves by rapidly flexing its wings something like a bat, 

 and was continually coursing around and in the wakes of the vessels, 

 generally in considerable numbers, during much the greater part of 

 the time that the Expedition was in the Atlantic Ocean." 



Subsequently, we find in Dr. Pickering's Journal : 



" Thalassidroma Wilsoiiii was taken in the Atlantic, in latitude 35° 

 south, and was seen occasionally as far as Cape Horn. In the Pacific, 

 it occurred at times until within a day's sail of Callao." 



Specimens, in good plumage and preservation, are in the collection, 

 and are from various and widely remote localities. 



2. Thalassidroma lineata, Pecde. 



Thalassidroma lineata, Peale, Zool. U. S. Exp. Exp. Bird.s, p. 293 (1st ed. 1848). 



Plate XXXIX. Adult 



T. mclanogastram refert. Saturate fallginosa, tectricibus caudae supe- 

 riorihus ahdomineque alhis, hoc lineolis fuliginosis notato. Long. tot. 

 li pollices. 



