VEETEBRATA. 237 



aquatic. Ichthyornis was about the size of a pigeon. Odonto- 

 pteryx toliapicus, from the Isle of Sheppey, regarded as*most 

 nearly related to Natatores, has bony processes of the jaws equi- 

 valent to teeth. 



*Ichthyornis. *Apatornis. 



*0dontopteryx. 



Order XIII. ODONTOLCLE. 



Jaws with the teeth in continuous grooves. " Vertebrae as in 

 birds. Sternum without a keel. Wings rudimentary." 



Extinct birds of large size, contemporaneous with the last. 

 They are also supposed by Marsh, to whom we owe all we know 

 of this and the preceding order, to have been carnivorous and 

 aquatic. Hesperornis he compares with the cassowaries and the 

 penguins. 



*Hesperornis. *Lestornis. 



Order XIV. SAUKUIkE. 

 UROIONI. 



Tail composed of numerous free vertebras, each carrying a single 

 pair of feathers. Sternum rudimentary. Metacarpal bones not 

 anchylosed. 



The first known specimen of the remarkable form (Archao- 

 pteryx lithographica) which alone constitutes this order was 

 found in 1861, in the lithographic limestone of Solenhofen, near 

 Munich. It was about the size of a pigeon, and was supposed to 

 have been web-footed and a fish-eater. A more perfect specimen 

 has recently been discovered. Two small conical teeth remained 

 in the upper jaw ; there was no appearance of a furcula, and the 

 sternum was " reduced to zero." The manus resembles that of a 

 tridactyle lizard. According to Vogt, its only bird-characters 

 were its feathers and feet. The tail, always a variable organ, 

 shows in this animal the persistency of what is now an embryonal 

 character. 



The Archcscpteryx is what Huxley has called an " intercalary 

 type," that is, not representing the direct passage from one group 

 to another. It would seem to lie somewhere between the gulls 

 (or perhaps falcons) and the extinct reptilian form Compso- 

 gnathus. 



*Archaeopteryx. 



