200 Bibliography. 



period, of a bird whose Iridactyle footprints, as will be presently shown, 

 surpassed the Ornithichnites giganteus of Prof. Hitchcock." 



By comparing the Ornithichnites giganteus with the track and foot 

 of the Ostrich, Prof. Owen concludes that " the breadth of the distal 

 end of the tarso-tnetatarsal bone of the tridactyle bird that impressed 

 the Ornithichnites giganteus, must have been three inches nine lines. 

 But the breadth of the distal end of the tarso-metatarsus of the Dinar- 

 nis giganteus, is five inches. According, therefore, to the proportions 

 of the Ornithichnites giganteus, the breadth of the hind part of the 

 footprint of the Dinornis giganteus must have been six inches, and its 

 length twenty one inches and a half." 



Prof. Owen can judge much better than we can, whether it is quite 

 safe to infer the breadth of the distal extremity of the tarso-metatarsus 

 of a tridactyle bird, from that of a didactyle bird. But admitting the 

 rule, we remark farther, that his measurements of the Ornithichnites 

 giganteus were taken, as we suppose, from a cast in the Hunterian 

 Museum, London, of the same size as the specimen figured in this 

 Journal for January, 1836. That was indeed a very safe specimen 

 from which to infer the size. But we have long been acquainted with 

 tracks of this species considerably larger, a description of some of 

 which is given in the present number of this Journal, (p. 63.) Yet 

 even these (from eighteen to twenty inches long) fall short of the foot 

 of Dinornis giganteus as calculated by Prof. Owen. He thinks that 

 the Dinornis struthoides, the third species in size, might have made a 

 track as large as the specimen of Ornithichnites giganteus to which 

 he refers, and that the " footprint of the Dinornis didiformis was prob- 

 ably about the size of the Ornithichnites tuherosus of Prof, Hitchcock." 



" From the foregoing comparison of the bones of the feet in the 

 different species of Dinornis with the impressions left by the ancient 

 birds of the American continent," continues Prof. Owen, " it must not, 

 however, be concluded that these were species of Dinornis. Agree- 

 ment in the size of the foot and number of the toes does not constitute 

 specific or even generic identity in ornithology, as the living Emeu, 

 Rhea, and Cassowary testify ; and though we may admit that the dis- 

 covery of tridactyle terrestrial birds of a size more gigantic even than 

 that indicated by the Ornithichnites giganteus and Ornithichnites in- 

 gens tends greatly to remove the skepticism with which such evidences 

 of the extinct animals of the Triassic period had been previously re- 

 ceived, yet the recognized succession of varying vertebrated forms in 

 the interval between that period and the present, forbids the supposition 

 that the same species or genus of birds could have maintained its ex- 

 istence throughout the several great changes which the earth's surface 

 has undergone during that vast lapse of time." 



