NO. II CLASSIFICATION, BIRDS OF THE WORLD — WETMORE 15 



brium, the different form of the posterior margin of the sternum, 

 which is entire or 2-notched, the straight outline of the palatines, and 

 in the ventral pteryla where the outer branch joins posteriorly to the 

 main tract. The Strigidae possess a manubrium, the sternum is 

 4-notched, the palatines are greatly expanded posteriorly, and the 

 posterior end of the ventral pteryla does not join the main tract at 

 the posterior end. 



Apodiformes. — Lucas (1889, pp. 8-13; 1895, pp. 155-157) long ago 

 demonstrated the differences between the true swifts and the crested 

 swifts, though his work seems latterly to have been overlooked, in view 

 of the recent inclusion of the two in one group, as by Stresemann and 

 by Mayr and Amadon. The skull in the Hemiprocnidae is quite dis- 

 tinct in the general form of the cranium and in the development of 

 the nasals, vomer, and palatines. The hypotarsus has a tendinal 

 foramen (like that found in hummingbirds), and the plantar tendons 

 have the flexor longus hallucis connected with the branch of the flexor 

 perforans digitorum, which extends to the fourth digit. Coupled with 

 this there may be noted the curious nest, which, fastened to the side 

 of a branch, is barely large enough to contain one egg, and the further 

 fact that these birds perch regularly on branches and twigs in trees. 



As Apits Scopoli, published in 1777, is recognized now in place of 

 Micropus Meyer and Wolf, 1810, for the type genus of the swifts, 

 the terms in the classification change to order Apodiformes, suborder 

 Apodi, and family Apodidae, which replace the former terms Mi- 

 cropodiformes, Micropodi, and Micropodidae, respectively. 



C orach 'formes. — The proposal of Mayr and Amadon (1951, p. 35) 

 to include the rollers in one family, the Coraciidae, with three sub- 

 families, goes back to the arrangement of Dresser in his monograph 

 of the group (1893, pp. xviii, 85, 101). Sclater (1865, pp. 682-688), 

 however, many years ago, pointed out the pelvic powder-down tracts, 

 the small manubrium, and other peculiarities of Leptosoma, and set 

 it apart in a distinct family. The anatomy of the syrinx and feet was 

 further elaborated by Forbes (1880, pp. 464-475). The family 

 Leptosomatidae therefore should be recognized. 



The groundrollers, Brachypteracias, Atelornis, and Uratelornis, 

 usually have been included as a subfamily of the Leptosomatidae, but 

 Stresemann (1934, p. 829) places them in a separate family, the 

 Brachypteraciidae. There seems to be reason for this in their general 

 appearance, though their anatomy is not well known. Brachypteracias, 

 in its skeleton, differs from Coracias and Eurystomus in the much 

 greater depth of the outer notch on the posterior border of the 

 sternum, in the much broader and stronger pelvis, the heavier femur, 



