344 CLASSIFICATIOX OF VERTEBRATES. 



of a crow, the other considerably larger. Laoptt-n^x, known 

 from a few fragments from the Jurassic of \\'yoming, may be- 

 long here. 



ORDER 11. ODONTORM.E. 



Extinct carinate birds with normal avian tail (pygostyle) ; 

 teeth thecodont ; presacral vertebras amphicoelous ; quadrate 

 with a single articular facet ; rami of lower jaw united by 

 cartilage. 



To this order belong a few birds arranged in the genera 

 Ichthyomis and Apatornis, pigeon-like in size, found in the 

 middle cretaceous of Kansas and Colorado. They had ver)- 

 large skulls, strong wings, and small legs, while the succession 

 of the teeth was vertical as in the dinosaurs. This and the fol- 

 lowing order are frequent!}- united as odontomithes or toothed 

 birds. 



ORDER III. ODONTOHOLC^. 



Extinct ratite birds with teeth in alveolar grooves ; vertebral 

 centres saddle-shaped ; quadrate with one articular facet ; skull 

 dromaeognathous ; rami of lower jaw united by cartilage ; ^^^ng 

 reduced, only the humerus retained. 



The birds belonging to this order occvu: in the same beds 

 as do the odontormae. In general appearance the}' were some- 

 what like grebes. The cranial bones were firmlv united, the pre- 

 maxillary bone was without teeth, while the teeth of the maxUlse 

 and lower jaw had a lateral succession as in the p^■thonomo^phs. 

 There was no true pygost}le, but the caudal vertebrae were 

 broadly expanded, forming a paddle-like tail, only a few of the 

 distal bones being fused. The cla\acles were not imited into 

 a wish-bone ; the acetabulum resembled that of the crocodiles ; 

 ilia, ischia, and pubes were not united posteriorh- ; and the feet 

 were apparently fitted for swimming onl}-. Here belong Hes- 

 pt-rornis and Lestornis. H. regalis was about six feet long ; 

 L. crassipes considerably larger. 



