NATURAL SCIENCES OF PHILADELPHIA. 21 



The Committee on Proceedings announced the publication of the 

 Proceedings for December, 1863. 



Dr. Wilcox presented for publication a continuation of his paper for 

 January 12th. 



February 23(Z. 

 Vice-President Bridges in the Chair. 



Twenty-two members present. 



The following was presented and unanimously adopted : 



Resolved, That the specimens of antique art belonging to the Aca- 

 demy be deposited in the Museum of the American Philosophical 

 Society, provided that they shall be returned oh demand, and that the 

 Curators of the Society shall give a receipt for the same to the Curators 

 of the Academy. 



On report of the respective committees, the following were ordered 

 to be published : 



The Crania of COLYMBUS TOBQUATTJS and C. ADAMSII compared. 

 BY ELLIOTT COUES, M. D. 



I have already, in a previous paper,* presented the external characters of 

 size, form, and color by which the C. Adamsii may be distinguished from the 

 common C. torquatus. To more completely substantiate the claims of the 

 former to specific distinction, which I understand is denied it by some orni- 

 thologists, I have taken advantage of an opportunity of comparing the crania 

 of the two species, to present the marked points of difference, as regards size 

 and shape, which an examination of the skulls shows to exist. It is per- 

 fectly easy to diagnose either species from the characters of their crania alone. 



As might be expected from the relative dimensions of the two birds, the 

 cranium of C. Adamsii is considerably larger than that of C. torquatus. The 

 difference is particularly striking in the length of the skull, taken as a 

 whole, as well as in the longitudinal dimensions of its individual elements. 

 The total length exceeds that of C. torquatus by fully an inch ; and the dif- 

 ference in the length of particular bones, as the intermaxillary, palatals, malars, 

 vomer, etc., is proportionately as much. In connection with this increase in 

 the length of skull, there is to be taken into consideration another point, 

 which confers upon the cranium of C. Adamsii a marked difference in general 

 contour, viz., its remarkable narroioness. In width at the several points, 

 the cranium by no means preponderates over that of C. torquatus in propor- 

 tion to its marked difference in length. Thus, is diameter across the fronto- 

 maxillary suture, or across the anterior or posterior orbital process, is, both 

 absolutely and relatively, but little greater than that of C. torquatus, while 

 across the mastoid processes the width is absolutely the same, and therefore 

 relatively less in C. Adamsii. 



The external character, which is perhaps the most distinctive feature of C. 

 Adamsii viz., the size and shape of the bill, corresponds, of course, to a like 

 modification of the proportions of the intermaxillary and inferior maxillary 

 bones. In fact, the difference in the relative proportions of the crania of the 



* Vide Proc. Acad. Nat. Sci., Philada.. April, 1S62. p. 227. 



1864.] 



