12 NORTH AMERICAN OOLOGY. PART I. 



with one from Greenland, in the collection of the Philadelphia Academy (fig. 12). 

 If these variations are specific, as I presume they are, the eggs belonging to Mr. 

 Yarrell, described by him as those of the European species (H. islandicus), are 

 probably those of the American bird. The same were figured by Mr. Hewitson ; 

 and as neither of these naturalists recognizes the two Hawks as distinct species, 

 they were not likely to be on their guard in reference to any specific variations in 

 their eggs. In European collections, the eggs of both species have been confounded 

 with each other, all passing as undoubted eggs of H. islandicus, precisely as those 

 of the American Fish-hawk (Pandion carolinensis) are unwarrantably confounded 

 with those of the European Osprey (Pandlon haluctus), and the two are even re- 

 garded as identical in Hewitson's Oology. 



The egg of the H. sacer is slightly larger than that of the H. islandicus, and the 

 predominant color of its markings is a deep reddish-brown, very generally and 

 nearly equally diffused over its surface, concealing the ground color, which is 

 lighter, and with a more yellowish shade. Its measurement is 2-^- inches in length 

 by ly-o inches in breadth. 



Two specimens of the egg of H. islandicus, one from Norway and the other from 

 Iceland, measure, the first 2-nr by l^f, the latter 2yV by IK inches. In both, the 

 ground color is a dirty yellowish-white. One is marked with spots, clottings, and 

 confluent blotches of yellowish-brown, interspersed with a few dashes of dark brown 

 in an increased proportion about the larger end. The other is marked in like 

 manner with light yellowish-brown, but much more sparingly, and so slightly and 

 uniformly, that, unless closely examined, it would seem to be of one uniform color, 

 and that a light brown, shaded with yellow. 



HYPOTRIORCHIS COLUMBARIUS. 



Falco columlarius, LINN. Syst. Nat. I, 1766, 128. 



WILS. Am. Orn. II, 1810, pi. xv, fig. 3. 

 " BONAP. Syn. 1828, p. 38. 



" RICH. & SWAINS. F. B. A. II, 1831, 35. 



" NUTTALL, Manual, I, 1832, 60. 



AUD. Orn. Biog. I, 1832, 466 ; V, 368, pis. Ixxv and xcii. 

 BONAP. Geog. and Comp. List, 1838, p. 4. 

 Arm. Syn. 1839, p. 16. 



" Birds of Am. I, 1840, 88, pi. xxi. 

 DE KAY'S Nat. Hist. N. Y. I, 1844, 4, pi. iv, fig. 9. 

 Falco intermixtus, DAUDIN, Traite d'Orn. II, 1800, 141. 

 ?? Falco ccsalon, RICH. & SWAINS. F. B. A. II. 1831, 37. 

 Falco temerarius, AUD. Orn. Biog. I, 1832, 381, pi. Ixxv. 



VULG. The Pigeon-Hawk. Little Corporal Hawk. L'Epervier de la Caroline (Briss.). 



IT was at first my intention to omit at present giving any plate representing the 

 egg of this species, for the reason that I have been unable to decide with certainty 



