THE CRETACEOUS PERIOD. 283 
aquatic members of the class of Birds with which we are ac- © 
quainted at the present day. It appears to have stood between 
five and six feet high, and its inability to fly is fully compen- 
sated for by the numerous adaptations of its structure to a 
watery life. Its teeth prove it to have been carnivorous in its 
habits, and it probably lived upon fishes. It is a curious fact 
that two Birds agreeing with one another in the wholly abnor- 
mal character of possessing teeth, and in other respects so 
entirely different, should, like /chthyornis and AHesperornis, 
have lived not only in the same geological period, but also in 
the same geographical area; and it is equally curious that 
the area inhabited by these toothed Birds should at the same 
time have been tenanted by winged and bird-like Reptiles 
belonging to the toothed genus P/erodactylus and the toothless 
genus Preranodon. 
No remains of JZammats, finally, have as yet been detected 
in any sedimentary accumulations of Cretaceous age. 
LITERATURE. 
The following list comprises some of the more important works and 
memoirs which may be consulted with reference to the Cretaceous strata 
and their fossil contents :— 
(1) ‘ Memoirs of the Geological Survey of Great Britain.’ 
(2) ‘Geology of England and Wales.’ Conybeare and Phillips. 
(3) ‘Geology of Yorkshire,’ vol. ii. Phillips. 
(4) ‘Geology of Oxford and the Thames Valley.’ Phillips. 
(5) ‘Geological Excursions through the Isle of Wight.’ Mantell. 
(6) ‘Geology of Sussex.’ Mantell. 
(7) ‘Report on Londonderry,’ &c. Portlock. 
(8) ‘Recherches sur le Terrain Crétacé Supérieur de l’ Angleterre et de 
VIrlande.’ Barrois. 
(9) *‘ Geological Survey of Canada” —‘ Report of Progress, 1872-73.’ 
(10) ‘Geological Survey of California.” Whitney. 
(11) ‘Geological Survey of Montana, Idaho, Wyoming, and Utah.’ 
Hayden and Meek. 
(12) ‘Report on Geology,’ &c. (British North American Boundary 
Commission). G. M. Dawson. 
(13) ‘Manual of Geology.’ Dana. 
) ‘Lethzea Rossica.’ Eichwald. 
(15) ‘ Petrefacta Germaniz.’ Goldfuss. 
(16) ‘ Fossils of the South Downs.’ Mantell. 
(17) ‘Medals of Creation.’ Mantell. 
(18) ‘ Mineral Conchology.’? Sowerby. 
(19) ‘ Lethzea Geognostica.’ Bronn. 
(20) ‘Malacostracous Crustacea of the British Cretaceous Formation’ 
(Palzeontographical Society). Bell. 
(21) ‘Brachiopoda of the Cretaceous Formation’ (Palzontographical 
Society). Davidson. 
(22) ‘Corals of the Cretaceous Formation’ (Palzeontographical Society). 
Milne-Edwards and Haime. 
