THE NIDIOLOGIST. 



183 



Recent Publications. 



COMPARATIVE Oology of North 

 American Birds. By R. W. Shn- 

 feldt, M. D. Rept. U. S. Nat. Mus. 

 for 1892, pp. 461-493. As stated by the 

 author, " The only object of this paper is 

 to bring together what is already well 

 known in regard to the Oology of North 

 American birds, placing it before the Orni- 

 thologist in a more condensed form than it 

 is usually given and in a comparative 

 way." The geologically earliest known 

 egg, that of j^pyornis, is compared with 

 those of _ the Ostrich types of birds and the 

 eggs of some of the least specialized species 

 are noticed in comparison with the eggs of 

 reptiles, particularly lizards, the eggs of 

 which are, with one exception, elliptical. 

 In noticing the variation in the general 

 shape of eggs, the author quotes Prof. New- 

 ton: "In form, eggs vary much, and this 

 is sometimes observable in examples not 

 only of the same species, but even from the 

 same mother, yet a certain amount of re- 

 semblance is usually to be traced according 

 to the natural group to which the parents 

 belong." This is in the main true, but 

 like many other general Oological laws sus- 

 ceptible to exceptions, a striking one of 

 which was in the case of a single female 

 Colaptes cafer which laid several clutches 

 in the same tree without accumulating 

 enough at any time to begin setting. 

 Among nearly or quite a score of eggs laid 

 were some which but for the texture of the 

 shell and color would never have been sup- 

 posed to be Picarian eggs. In form many 

 had lost the character of the PicaricB. Still 

 this exception was due partly to abnormal 

 conditions, the eggs being taken always 

 before a full complement was deposited. 



The main feature of Dr. Shufeldt's paper 

 is the comparison, usually in parallel col- 

 umns, of the published descriptions (and 

 discrepancies) of authors in regard to the 

 number of eggs laid, their color, size, etc., 

 making the paper an important one for Ool- 



ogists, as well as strongly emphasizing the 

 importance of having some standard nomen- 

 clature of colors to which reference may be 

 made, the terms used then being clear to 

 all. Such a standard has been prepared by 

 Mr. Ridgway, leaving no excuse for vague- 

 ness in descriptions of eggs. In conveni- 

 ent reference tables are compiled the des- 

 criptions, so far as they have been pub- 

 lished, of the eggs of the orders of North 

 American birds by Coues, Ridgway and 

 Bendire. 



In speaking of the deposition of the 

 color pigment Prof. Newton is quoted, and 

 it may be new to some to know that, al- 

 though not stated in the paper under con- 

 sideration, the shell spots and markings of 

 the eggs of a California Guillemot of the 

 brown-marked series are all caused by one 

 color-pigment, as may be easily determined 

 by scraping the shell with a sharp knife 

 over one of the lavender shell-spots; grad- 

 ually it will become as dark as any of the 

 superficial blotches, showing conclusively 

 that but one pigment has given the two 

 colors, and that the light markings only ap 

 pear so because they are deep-seated and 

 actually congenital with the formation of 

 the shell. On the other hand the egg of 

 the California Partridge has both the mark- 

 ings and the ground color superficial, as 

 hard-shelled, unlaid eggs are white until a 

 few hours at most of their deposition. Di- 

 luted oxalic acid will also demonstrate the 

 superficial character of all the colors, re- 

 moving them and leaving the egg pure, 

 lusterless white. There is a hint here for 

 further stud}^ in the coloration of eggs, and 

 a suggestion that the microscope be em- 

 ployed to determine what relationship or 

 differences, if any, exists in the texture or 

 grain of the shell. Ten laws are formu- 

 lated from various authors, to account for 

 the variations in the color of the shells of 

 birds' eggs, and in his concluding remarks 

 Dr. Shufeldt briefly reviews the Oological 

 peculiarities of North American birds in 

 the light of these same laws, but encouu- 



