II NEORNITHES ODONTOLCAE 45 



thidae ; while the nostrils are pervious, and the quadrate articu- 

 lates with the skull by two heads, contrary to what occurs in the 

 Ratitae proper. The furcula is existent, but extremely slender ; 

 the metatarsvis is more or less elongated, the hallux is present, 

 the wings are small but well developed, and the tail is said to be 

 long, with a considerable number of separate vertebrae. 



This genus includes tlie species P. longissimus, P. injiatus, P. 

 'platygnatlius, P. modicus, P. gracilis, and P. sehuensis ; Brontornis, 

 which has a shorter and wider mandible and smaller but stouter 

 metatarsi, possesses in B. burmeisteri a form as large as Aepyornis 

 maxiinus, while Opisthodactylus and other proposed genera are too 

 imperfectly known to deserve consideration in our limited space. 



Besides the above, Dr. Gadow classed with the Stereornithes, 

 Diatryma of New Mexico, known from a metatarsus ; Dasornis of 

 the London Clay, described from fragments of a skull ; Remiornis 

 from the neighbourhood of Eheims, of which several imperfect 

 1 lones have 1 >een found ; and Gastornis of both England and France, 

 of which a fair number of parts have been unearthed. All occur 

 in the Eocene, but the question of their relationship is by no 

 means settled, and some writers consider Gastornis to be nearly 

 allied to the Anseres. This form appears to have been of the size 

 of an Ostrich, with long leg-bones and short weak wings, and 

 was probably flightless. Three species have been propounded, 

 G. 2)arisie7isis, G. Jdaasseni, and G. rdvardsi. 



(B) With regard to the difficult question of the position in the 

 system of the Neornithes Odontolcae, a few introductory words 

 of explanation are necessary. In 1872 Professor Marsh bestowed 

 upon two fossils from the Cretaceous deposits of Kansas the 

 names of Hesperornis and Ichthyornis, which he proposed in the 

 following year ^ to comprise in a Sub-Class Odontornitlies, so called 

 from the presence of teeth in the jaws. Subsequently " he divided 

 this Sub-Class into two Orders, Odontolcae and Odontotormae, the 

 former containing Hesperornis, with the teeth arranged in grooves, 

 and the latter Ichthyornis, where they were placed in distinct 

 sockets. His views have been controverted by many writers, 

 but Mr. Lydekker — an authority of great weight in tliis con- 

 nexion — while fully admitting the affinity of the first form to 

 1 Amcr. J. Sci. (3) v. 1873, pp. 161, 16'J. - Cy;. cU. x. 1875, pp. 403-108. 



