Prof. Nicholson — Progress in Palmontohgy, 11 



and diver, and it probably lived upon fish, which it captured by 

 means of its toothed jaws. Its tail was not long and lizard -like, as 

 in Archceopteryx, but consists of about twelve vertebrse., of which 

 the last three or four are amalgamated to form a flat terminal mass, 

 there being at the same time clear indications that the tail was 

 capable of up-and-down movement in a vertical plane, this probably 

 fitting it to serve as a swimming paddle or rudder. The vertebrae 

 of the cervical and dorsal regions are of the ordinary well-known 

 ornithic type. 



In the OdontotormcB — the second order of Odontornithes — the 

 type-genus is the wonderful Iclitliyornis, which, though apparently 

 aquatic in its habits, differed from Hesperorms in having well- 

 developed wings, constructed upon the usual ornithic type. The 

 jaws were furnished with compressed pointed teeth, which were 

 sunk in distinct sockets. The vertebree, further, have the absolutely 

 unique character — a character unknown in the entire class Aves — 

 that their bodies were bi-concave. In this respect, therefore, Ichthy- 

 ornis makes an approach to the Fishes, Amphibians, and Keptiles, in 

 which amphicoelous vertebrae are common, or occur in certain groups. 

 The tail of Ichihyornis, as of the allied Apatornis, is unfortunately not 

 known. 



The second discovery among Birds to which allusion ought to be 

 made is that of the Odontopteryx toliapicus of the London Clay, de- 

 scribed by Prof. Owen. This very singular bird exhibits the peculi- 

 arity that the osseous margins of the jaws are prolonged into tooth- 

 like extensions, which are of two sizes, and which were probably 

 encased in prolongations of the horny substance of the bill. These 

 processes are triangular, compressed, and directed forwards, and 

 they are not to be confounded on the one hand with the denticula- 

 tions found in the horny sheath of the bill of various living birds, 

 or on the other hand with the genuine teeth possessed by the 

 Odontornithes. Professor Owen concludes that Odontopteryx was 

 probably aquatic in its habits, and he regards it as a natatorial bird 

 allied to the AnatidoB. 



Coming, finally, to the Mammals, the discoveries which have been 

 made within the last few years, more particularly those which have 

 resulted from the researches carried on by Marsh, Leidy, and Cope 

 into the Tertiary Mammals of North America, have been so numerous 

 and so important, that my time to-night will not permit me to do 

 more than simply to allude to a few of the more important ones, 

 and more particularly to those by which changes have been effected 

 in the previously existing systematic arrangement of the Mammalia, 

 or which have fundamentally altered our conceptions of the character 

 of certain groups. 



Among the Monotremes, Krefft records a gigantic Echidna from 

 the Post-Tertiary deposits of Australia. As regards Marsupials, I 

 may merely mention the recent appearance of Prof. Owen's magnifi- 

 cent work on the Fossil Mammals of Australia, in which will be 

 found the fullest record extant of all that is known as to the wonderful 

 extinct Marsupials which ranged over Australia in Post-Tertiary 

 times. 



