IN TIIK UULF OF OMAN. 293 



their wandering" course for some distance with rapid strokes of 

 the wing. They have a peculiar Plover-like habit, when flying 

 of turning from side to side, looking dark one second, and light 

 the next, as they show their white breasts and dark backs 

 alternately. 



The measurements of the specimen I shot were as follows : — 



Sex. L. W. T. Bf. Bg. Exp. Ts. 



? 13- 787 35 12 175 27- 15. 



Legs white, with an opalescent gloss ; lower part of tarsus 

 and outer toe blackish ; outer side of centre toe and under side 

 of all the toes dusky black ; bill pale lavender, dusky at tip 

 and on the upper mandible ; irides dark brown. 



[This second specimen of Pitffinus persicus, also a female, 

 has the quills perfect, and the wing measures 7'87. The females 

 in this genus run rather smaller than the males, so that in this 

 latter sex the wings will certainly measure 8'0. 



This specimen is precisely like the type, except that it has 

 more white on the sides, and less on the lores. There is the 

 same white ring round the eye, and the same streak, but less 

 well defined, backwards, from the eye. 



Mr. Blanford (Ibis, 1873, p. 215 ; Zool. Per?., 293) considers 

 that he has shown that this is probably a variety of P. obscurus; 

 but agrees with me that it is certainly not anglorum. Of 

 this latter there is now no doubt, as I have compared speci- 

 mens. 



As to obscurus, my bird is certainly not the species identified 

 by Yarrel as the Dusky Petrel, of which he measured 6 speci- 

 mens, all of which had the wings 6 '75. 



Nor is it the obscurus of Temminck (Man. d'Orn, 2nd edition, 

 808,) with the <l Bee tres grele" (for the bill is as stout as in 

 anglorum,) and the tarsus 1'65, (that of both our birds being 

 barely 1*5.) 



But it might for all that be the true obscurus of Gmelin 

 (S. N. I. 559.). 



This was founded on the Dusky Petrel of Lath., Syn. III. 

 2,416. 



Latham's description is as follows : — 



" Length 13 inches ; bill one inch and n half; colour black, 

 with horn-coloured sides, point hooked ; in the usual place only 

 two small holes serving for nostrils ; the upper parts of the 

 body dusky black, the under white ; on the sides of the neck 

 brown and white mixed ; the edges of the middle wing coverts 

 are whitish. The legs placed quite in the vent, black, but the 

 inside pale the whole length and t'ie two inner toes yellowish ; 

 the webs orange ; claws black. 

 '* Inhabits Christmas Island." 



N 13 



