Bhijncliojnnce (Skimmers). Dr. Cones, in his Monograph of the North- 

 American Larida' (' Birds of the North-West,' pp. 589-717, 1874), 

 says (p. 592) that " the liliynchop'ma are in every respect true Terns 

 except in the feature of the unique bill." He adds : — "Examination 

 of the internal characters of the four subfamilies, Lestridina> [ = 

 Stercorainince^, Larhia; Siernince, and Rhyncliopinm, demonstrates 

 that the first and second and the third and fourth are more nearly 

 related to each other than are the second and third.'" This arrange- 

 ment of the four subfamilies is maintained by Dr. Coues in his ' Key 

 to North-American Birds,' 2nd ed. (1884). The compilers of the 

 American Ornithologists' Code and Check-List, pp. 84-97 (1886), 

 ■went further, and, while restricting their Longipeunes to the Gavige, 

 they divided this Order into three families — Stercorariidcv , Laridce 

 (subfamilies Larince and Sternince), and Rliiincl^opida' . These three 

 families are also adopted by Mr. Ridgway in his ' Manual of North- 

 American Birds,' p. 20 (1887). They are upheld by Dr. Shufeldt in 

 his papers " Comparative Osteological Notes on the Extinct Bird 

 Ichthyornis" (Journ. Anat. & Phys. xxvii. pp. 336-342) and "On 

 the Classification of the Longipennes " (Amer. Nat. 1893, pp. 233- 

 237). He considers that " BhyncJiops is, in some of its osteological 

 characters, notably in the skull, the vertebral chain and pelvis, not 

 very unlike the fossil cretaceous bird IcJitJiyornis." He is, more- 

 over, of opinion that the Stercorariidce " stand between the Laridce 

 and the MhyncJiopidci', being more nearly related to the first-named 

 than they are to the Skimmers.'' These views are deserving of con- 

 sideration and may eventually prove to be correct, but at present 

 the evidence seems insufiicient to justify their adoption in this 

 volume. 



Dr. Coues has, however, clearly shown the important characters 

 in which the Stercorarvidcp differ from the Laridce (points which 

 seemed to have escaped some later writers), and I have no hesita- 

 tion in accepting these two as families. They have been adopted 

 as subdivisions by Dr. E.. Bowdler Sharpe in his ' Review of Recent 

 Attempts to Classify Birds,' p. 72 (1891) ; and I further agree with 

 him that, for the present, it is undesirable to elevate the Rhynclio- 

 pince to the rank of a third family. 



In these introductory remarks the references have been carefully 

 restricted to those writers whose works had a very direct bearing 

 upon the classification of this Order ; but I am also indebted to the 

 treatises of Professors Huxley and Newton, the late A. Garrod and 

 W. A. Forbes, Drs. Piirbringer, Gadow, and Stejneger, Mr. Seebohm 

 and others, in addition to the authorities already cited — and, among 

 the last, especially to Dr. Elliott Coues. 



