NO. II CLASSIFICATION, BIRDS OF THE WORLD — WETMORE 13 



large as a medium-sized curlew, of peculiar form as regards the 

 foot, the only part of the skeleton known, which shows certain char- 

 acters that seem to point toward the jacanas, though the bird is to 

 be placed in the Charadrioidea. 



It should be noted that the family affinity of the turnstones and the 

 surf bird, long considered members of the plover family, is not certain 

 as some studies (Lowe, 1931, pp. 747-750) place them in the Scolo- 

 pacidae. (See also Bock, 1958, pp. 85-86.) 



In the Lari the terns and the gulls are regarded as one family, 

 though there are some reasons that make further examination of this 

 treatment desirable. The Stercorariidae possess a 2-notched sternum, 

 large caeca, a cere, and a complex rhamphotheca. In the Laridae 

 ambiens and biceps slip are present, the sternum is 4-notched, there 

 is no cere, and the rhamphotheca is simple in form. 



In further discussion of proposals relative to this group it is 

 pertinent to observe that a logical scheme of classification should 

 attempt to outline relationships in living and fossil species through 

 examination of all available data, considerations in which modern 

 studies of behavior find increasingly useful part. There are pitfalls 

 and hidden traps, however, when attempt is made to establish affiliation 

 through any single method of approach, as inevitably inconsistencies 

 appear. I fully agree with Martin Moynihan (1959, pp. 22-23, 35"38) 

 that the skimmers (Rynchops) represent an early separation in the 

 ancestry of the gull-like birds and find it pertinent that this is shown 

 in their behavior pattern. At the same time these birds present out- 

 standing peculiarities that should be considered in assigning them ap- 

 propriate status in relation to their relatives. The bill, compressed 

 to knifelike form, with great elongation of the ramphotheca of the 

 lower jaw, is unique, and the method of feeding, where the lower 

 mandible cuts the water surface with the bird in flight, is equally 

 strange. The structural modifications in the form of the skull from 

 that found in skuas, gulls, and terns also are too extensive to be 

 ignored. The elongated blade of the lower mandible anterior to the 

 symphysis of the rami is intriguing but less important than the pro- 

 found changes elsewhere. The palatine bones are greatly expanded, 

 the orbital process of the quadrate is reduced to a short, pointed 

 spine, the impression for the nasal gland is much reduced, the frontal 

 area is inflated and produced posteriorly, with compression of the 

 lachrymal, and consequent reduction in size of the cavity for the eye, 

 to enumerate the most outstanding differences in the osteology. Ex- 

 ternally, the pupil of the eye is a vertical slit similar to that of a cat, 

 and thus unlike that of any other group of birds (Wetmore, 1919, 



