FALCO EICHAEDSONII, AMERICAN MERLIN. 347 



stateaient, iu his later work, where he says he has no authentic iufor- 

 mation of its breediug in New England (p. 18). He, however, figures an 

 egg, received from Mr. Boardman as being of this species, from Mill- 

 town, Maine. It measures only 1.50 by 1.44, and in coloration, as rep- 

 resented on the plate, difl'ers materially from any authentic specimens 

 I have seen. It may be here remarked, moreover, that the egg figured 

 and described by Dr. Brewer proves not authentic, he having been 

 deceived by a chain of circumstantial evidence he could not but accept 

 as conclusive. In the uncertainty, I am the more pleased to offer an 

 unquestionable description, derived from examination of specimens iu 

 the Smithsonian. The size varies from 1.50 by 1.30 to l.SO by 1.30— 

 figures also indicating the range of variation in shape, some being sub- 

 spherical, others elongate-oval. Coloration ranges from a nearly uniform 

 deep rich brown (chestnut or burnt sienna), to whitish or white only, 

 marked with a few indistinct dots ot dull grayish or drab. Such ex- 

 tremes aie connected by every degree; a yellowish brown ground-color, 

 irregularly splashed with rich ruddy brown, is the usual style. The 

 markings may be very evenly distributed, or mostly gathered iu a 

 •wreath around one or the other end, or even both ends. 



I may here mention a fact in oology, apparently not without its value. 

 In measuring many hundred eggs, I have noticed that the variation, 

 however great, is less in absolute bulk than in contour — in approach to, 

 or departure from, what may be regarded as the standard of shape for 

 the species. Xow this variation in shape is produced mainly by 

 difference in the length of the mnjor axis, the transverse diameter being 

 approximately constant. What additional variation in shape may occur, 

 results from slight shifting of the point of greatest breadth toward one 

 end or the other. Anatomical considerations bear this out. Taking 

 the calibre of the oviduct as an approximately fixed quantity iu the 

 same species, and remembering that varying circumstances of age, sea- 

 son, and physical vigor, determine the amount of fluids secreted to 

 envelope the ovum, it is evident that, while the whole capacity of the 

 calcareous shell must vary correspondingly, the difference will be 

 mainly in lengthening or shortening of the egg-, since the contractility 

 of the oviduct holds the transverse diameter newly fixed. ^ 



There aie also few instances of greater difiereuce in the amount, 

 intensity, and distribution of pigmentary matter than those occurring 

 among Hawks, and even in eggs of the same nest-complement. I 

 think it a probable rule, that the succession of laying of the eggs can 

 b6 judged by the quantity of pigment iu the shell, those first extruded 

 being generally the most heavily colored, the others growing lighter 

 with gradual consumption of the color supply. This is strikingly illus- 

 trated in cases where the same nest has been robbed repeatedly — the 

 later laid eggs gradually losing their coloration, as well as gradually 

 growing smaller, with increasing exhaustion of the reproductive pow- 

 ers of the parent. Every poultry man is familiar with the extreme 

 instance of this, when a hen drops an egg often no longer than a 

 pigeon's, as the final effort before ceasing to lay. 



FALCO EICHAEDSOXII, Eidgw. 



American Merlin, 



FaUo ersalmi, Sw. &. Rich., F. B. A. ii, 1^31, ;!7, pi. 25 (excl. syn.; nee (7Hct).— Nutt., 

 Mau. ii, ls:u, B.Sy.— Tnwxs., Narr. ie:».— Coop, .t Suck., X. H. Wash. Ter. 

 1,-^60, •JtfS.— CoUES, Pr. Phila. Acad. 1866, 43 (iu text). 



Ht/poti-iorehis eolvmbarius, Cass., 111. 1854, 90 (partly).— Hayd.. Eep. 1862, 152.— Stev., 

 U. S. Geol. Surv. Ter. 1870, 462 (paxtly). 



7 



