257 



November 17, 1847. 



J. C. Warren, M. D., President, in the Chair. 



Dr. Cabot read a paper entitled " A Comparison between 

 Sterna Cantiaca, Gm. of Europe, and Sterna acuflavida, 

 Nobis, hitherto considered identical with S. Cantiaca;'' 

 specimens were exhibited. The following measurements 

 from adult, full-plumaged specimens were given : 



American. Mil 



Bill along ridge 



" " gape .... 



From the nostril to the point of the bill . 



Length of nostril .... 



Length of lower mandible along the cen- 

 tre, (measuring to the feathers,) 



Length of do. do. along the side, do. do. 



Width of bill at commencement of 

 feathers 



Depth of do. do. do. ... 



Length of wing from flexure 



Length of tail to tips of lateral feathers 



Length of tarsus ..... 



Middle toe without the claw 



Middle claw ..... 



Inner toe with claw 



Outer do. do 



Thumb ...... 



Besides these differences in measurement of parts not subject 

 to change from improper stuflino, &c., we find that the coloring 

 differs in some very important particulars. In the American 

 bird the yellow is strictly confined to the tip of the bill, and the 

 line of union of the yellow and black is perpendicular and unbro- 

 ken, whereas in the European bird the yellow runs up to the 

 inner edge of the symphysis on the under side of the lower man- 

 dible, and almost as far on the upper edge ; and on the upper 

 mandible also, it extends both on the edges and on the ridge 

 much higher than in the American bird. The primaries are 



