276 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



but not overlapping; toes 4, the hallux functional, incumbent, its 

 basal phalanx as long as that of middle toe, connected with the flexor 

 longus hallucis, not with the flexor perforans digitorum, the two 

 deep plantar tendons united by a vinculum; flexors of Type I 

 (Galline); thigh muscle formula ABX+or ABXY; intestinal con- 

 volutions of type V (cyclocoelous) ; biceps slip present, peculiar in 

 form; expansor secundariorum present; caeca nonfunctional, gener- 

 ally rudimentary; gall-bladder usually absent (present in genera 

 Muscadivores and LopJiolaimus) ; syrinx with one pair of asymmetrical 

 extrinsic tracheal, or tracheo-bronchial, muscles; two carotid arteries; 

 biceps slip present, peculiar in form; crop large, more or less protu- 

 berant; oil gland (if present) nude, sometimes absent; aftershaft 

 absent or rudimentary; adult downs absent; spinal pteryla well- 

 defined on neck by lateral apteria, forked on interscapular region; 

 primaries 11; secondaries 11-15, usually aquinto-cubital (quinto- 

 cubital in Columbula); rectrices 12-20. 



The Columbiformes agree with the Charadiiformes in the follow- 

 ing characters: Palate schizognathous; nares schizorhinal, pervious; 

 cervical vertebras 15 (except in (Edicnemidse and Jacanidse of the 

 latter, which have 16); primaries 11; secondaries acquinto-cubital 

 (mostly) ; hallux connected with flexor longus hallucis, not with flexor 

 perforans digitorum. They differ, however, in heterocoelous (instead 

 of opisthoccelous) vertebrae; usually 4-notched (rarely 2-notched); 

 sternum; absence or imperfect development of aftershaft to the con- 

 tour feathers; absence of oil gland (or if this is present it is nude 

 instead of tufted); incumbent and well-developed (instead of ele- 

 vated and reduced, often absent) hallux, and gymnopsedic and nidi- 

 colous young. 



They agree with the Pterocloformes in schizorhinal nares, rudi- 

 mentary vomer, usually 4-notched sternum, nude oil gland (if pres- 

 ent), aquinto-cubital secondaries, and some other characters, but 

 differ in the well-developed, functional, and incumbent hallux, 

 absence of aftershaft (or else this rudimentary), very different (Co- 

 lumbine instead of Galline) bill, gymnopsedic and nidicolous young, 

 immaculate eggs, and other characters. 



It is to the above groups that the Columbiformes are most nearly 

 related; indeed, the Order Columbiformes is by some authors made 

 to include not only the Charadriiformes in their most extended sense 

 (that is to say, Limicolse + Lari+Alcse), but also the Pterocletes. 

 The pigeons themselves, however, constitute, like the parrots, one 

 of the most sharply circumscribed groups of birds, and therefore seem 

 well entitled to rank as a distinct Order. 



