S48 THE AMERICAX NA TURALIST. [Vol. XXXVIII. 



suborder. To my mind such divisions can be very profitably 

 employed to express the normal relationships of birds as they 

 exist, and the relative nearness to each other of the various 

 groups as compared with other natural assemblages of the 

 Vertebrata. 



Passing now to the consideration of the second order of birds 

 (Order II, Ornithurae) we meet at first with the array of the 

 so-called ostrich forms it contains, or supersuborder II. These 

 represent some of the lowest types of existing bird forms, and a 

 number of extinct species allied to them have been discovered. 

 It will not be necessary to discuss the systematic position of the 

 Dromaeognathas (supersuborder II) for the reason that I have 

 already recently done so in a paper published in The American 

 Naturalist (Vol. XXXVII, No. 433, January. 1903, pp. 33-64- 

 2 figures), and this likewise applies to the supersuborder III, the 

 Odontoholcae. The Odontoholcje are placed next in order after 

 the ostrich-forms not for the reason that they possessed anything in 

 their osseous systems that in any way connected them with the 

 Dromaeognathae, but because they represent the archaic ances- 

 tral stock from which has been derived the existing Supersub- 

 order Colymbo-Podicipitiformes (IV) containing the loons, divers, 

 and grebes, and these last in the matter of organization stand 

 among the lowest of known types of modern birds. 



This group has been thoroughly treated in my published 

 papers. A few of the more important groups, however, are still 

 in press, as for example the "Osteology of the Accipitres " 

 (Carnegie Museum) ; - Osteology of the Anseres " (Carnegie 

 Museum); and the "Osteology of the Lariformes " (complete 

 in manuscript). I now offer my scheme for A Classification of 

 I'^irds. This classification requires in some of the groups illus- 

 tiatL.ns in the way of bird skeletons that I have heretofore been 

 unable to publish, and which will throw additional light upon 

 the subject. These have been kindly photographed for me at 

 the U. S. National Museum at Washington, and reproductions 

 ot those photographs are herewith presented, with the necessary 

 descriptions. 



