ORDER CARINAT.E. 



1231 



Suborder i. Odontorivle. — The one suborder which is the 

 only known representative of this series contains the family Ichthy- 

 ornithidce, from the North American Cretaceous, of which Ichthy- 

 ornis is the only definitely known genus, although it is highly prob- 

 able that Apatomis, and some of the other Cretaceous forms already 

 mentioned, may also belong to this or an allied family. The teeth 

 of Ichthyornis (fig. n 17, a) are comparatively large, and are set in 

 distinct sockets ; while the centra of the vertebrae are amphiccelous. 

 There were about twenty teeth in each jaw, which are directed ob- 

 liquely backwards. The rami of the mandible were but loosely 

 united ; and it is probable that the jaws were not sheathed in horn. 

 The adult of the typical I. dispar (fig. 1 1 1 6) was about equal in 

 size to a Rock-pigeon ; and in all essential features of its organisa- 



Fig. 1117. — a, Left ramus of the mandible of Ichthyornis, slightly enlarged ; b, Do. of Hes- 

 perornis, about one-fourth natural size ; c, c', Anterior and lateral aspects of cervical vertebra of 

 Ichthyornis, twice natural size ; d, Tooth of Hesperornis, twice natural size. (After Marsh.) 



tion this genus conforms so exactly with the existing Carinate type, 

 that there appears every reason for including it in the same order, 

 rather than following Professor Marsh's view of placing it, together 

 with Hesperornis, in a separate order under the name of Odontor- 

 nithes. 



Toothless Series. — In this series, which comprises all existing 

 Carinates, no teeth are ever functionally developed, although germs 

 occur in the young of one group. 



Suborder 2. Crypturi. — The Tinamous (Tinamus, &c.) which 

 constitute this suborder, show more signs of affinity in the structure 

 of their pelvis and skull to the Ratitae, than is exhibited by any 



