NATATORES. 457 



Genus HALOByENA, Is. Geoff, de St. Hilaire. 



The single species of this genus assimilates to the Prions in 

 its outward appearance, but is, in my opinion, more nearly 

 allied to the true Petrels. 



Sp. 634. HALOBJENA CGERULEA. 



Blue Petrel. 



Procellaria cosrulea, Gmel. Edit, of Linn. Syst. Nat., torn. i. p. 560. 

 Blue Petrel, Lath. Gen. Syn., vol. vi. p. 415. 

 Procellaria similis, Forst. Draw., No. 86. 



forsteri, Smith, Zool. of S. Africa, Birds, pi. 54. 



Halabcena ccerulea, Bonap. Compt. Rend, de VAcad. Sci., torn. 1856. 



Procellaria ccerulea, Gould, Birds of Australia, foL, vol. vii. pi. 52. 



This bird may be distinguished from every other of the 

 smaller Petrels by the conspicuous white tips of the centre 

 tail-feathers. It is a very powerful flier, and I observed it in 

 every part of the ocean I traversed between the 40th and 55th 

 degrees of south latitude, both in the Atlantic and Pacific. 



It is generally seen in company with the fairy -like Prion 

 turtur, from which when on the wing it can scarcely be dis- 

 tinguished, unless it passes sufficiently near for the observer 

 to note the more square form, and the white tips of the tail- 

 feathers, which, as well as the silvery ends of the secon- 

 daries and scapularies, show very conspicuously. On my 

 passage to Australia I first observed it in lat. 39° 23' S., long. 

 54° E.; as we proceeded it gradually increased in numbers, 

 and was very plentiful off the coast of Tasmania ; I also met 

 with it in my passage from Hobart Town to South Australia 

 and Sydney ; and on my return to England in the beginning 

 of May 1840, I observed it to be very abundant off the north- 

 east coast of New Zealand ; tolerably numerous on the 20th 

 of May near Cape Horn, lat. 50° S., long. 90° W. ; plentiful 

 midway between Tristan d' Acunha and the coast of America ; 



