THE GENUS CHORDEILES SWAINSON — OBERHOLSER. 9 



The genera in the above lists are arranged in what seems to be 

 their natural order, but manifestly the osteology of all must be 

 studied before a finally satisfactory sequence can be devised. The 

 Chordeilidae, by reason of their desmognathism and the loss of the 

 gall bladder, seem to be a less ancient and less primitive group 

 than the Caprimulgidae. The full and formal diagnosis^ of the 

 Chordeilidae, based, of course, almost entirely on Chordeiles, is as 

 follows : 



CHORDEILIDAE, new family. 



Caprimulgi with sternum one-notched on each side; carotids two; 

 syrinx tracheo-bronchial ; oil gland present; cseca present; cervical 

 vertebrae 13; fourth (outer) toe with but four phalanges; claw of 

 middle toe pectinated ; muscular formula AXY ; biceps slip present ; 

 expansor secondariorum absent; glutaeus pnmus extending over bi- 

 ceps; gall bladder lacking; powder downs absent; skull broad, the 

 zygoma spreading and distinctly angular, the interorbital breadth 

 great; braincase high; frontals medially concave; premaxillary 

 short, only 37 per cent of total length of skull ; palate perfectly des- 

 mognathous; maxillo-palatines relatively broad and subtriangular, 

 ankylosed with each other and with the vomer; palatines much in- 

 flated posteriorly and across their middle portion, not meeting except 

 at their hind ends, the foramina in their middle portion small, their 

 lateral outines little constricted medially, their antero-external proc- 

 esses long and slender, their antero-internal processes reaching to the 

 maxillo-palatines; vomer long, slender, and pointed at its anterior 

 end ; basipterygoid processes well developed ; rictal bristles wanting. 



The type genus of this family is Chordeiles Swainson. 



The geographical range of the family is as follows : South Amer- 

 ica, Central America, North America, and the West Indies; thus 

 practically all of the Neotropical and Nearctic zoogeographical 

 regions. 



The genera to be included in the family Chordeilidae have already 

 been discussed.^ 



In making comparisons of the skulls of Chordeiles with those of 

 several genera of true Caprimulgidae some interesting facts concern- 

 ing the latter family were discovered. The current genus Antro- 

 stomus Bonaparte, by many authors considered to include a well- 

 known group of American species, by others united with Caprimul- 

 gus, is not only perfectly distinct from the latter, but is itself divisible 

 into two very divergent groups. In the following comparisons the 

 skulls of only three species, Caprimulgus europaeus, Antrostomus 



^ Characters common to all Caprimulgi are omitted. 

 2 See p. 8. 



13732°— Bull. 86—14 2 



