6 5 2 



ODONTORNITHES 



Greensand, named by Prof. Seeley in 1869 Enaliornis, and the 

 closely allied Baptdrnis from the North American Cretaceous (see 

 FOSSIL BIRDS). While possessing heteroccelous cervicals, it is 

 believed that Enaliornis had its dorsal vertebrae amphicoelous. 



Retaining in their amphicoelous vertebrae evidence of their 

 reptilian ancestry which is lost in the more specialized Hesperornis, 



Fig. 6. 



CERVICAL VERTEBRA OF ICHTHYORNIS, 

 FROM FRONT AND SIDE. 

 (As before, after Marsh.) 



Fig. 5. MANDIBLE OF ICHTHYORNIS. (As before after Mars'.i.) 



the small Gull-like birds known as Ichthyornis may probably be 

 regarded as holding a somewhat more intimate relationship to the 

 modern LIMICOL^E and GAVLE than is presented by the former to 

 the PYGOPODES, the specialization connected with the absence of 



flight in the former genus being want- 

 ing. Traces of affinity with Ichthyornis 

 are, indeed, indicated by the more 

 or less markedly opisthocoelous dorsal 

 vertebras of the Limicolaz and Gaviaz ; 

 but whereas both these groups have 

 an ectepicondylar process to the 

 humerus, and an extensor bony bridge 

 to the tibio- tarsus, neither of these 

 features are present in the cretaceous 

 genus. The fenestration of the meta- 

 carpus characteristic of the Gavise is, moreover, wanting in 

 Ichthyornis. Hence it would appear that we must regard all 

 the above-mentioned features characterizing the existing groups 

 named as of comparatively late origin ; while the differences 

 between the extinct and living forms appear to the writer far too 

 important to admit, as has been proposed, of their inclusion in 

 a single ordinal group. Although Apatornis, from the Yellow Chalk 

 of Kansas, and as yet imperfectly known, was apparently an allied 

 type, distinguished by the great development of the acromial pro- 

 cess of the scapula, and the stouter hind limbs, the remaining 

 genera of (? toothed) birds from the same horizon referred to the 

 Odontornithes are named on the evidence of such incomplete 

 remains, that it is impossible to speak of their affinities with 

 certainty ; all that can be said for them will be found in their 

 describer's magnificent work forming the first volume of the 

 Memoirs of the Peabody Museum of Yale College. 1 



RICHARD LYDEKKER. 



1 Odontornithes : a Monograph on the Extinct Toothed Birds of North America. 

 By Othniel Charles Marsh. Fol. New Haven, Conn. : 1880. 



