54 Prof. R. Owen on the Occurrence 



Fossil Reptiles " for 1841*, a genus Leiodon was defined on a 

 modification of mosasauroid teeth in a fragment of jaw dis- 

 covered in a Cretaceous formation in Norfolk, and figured in 

 plate lxxii. figs. 1, 2, of my ' Odontography.' 



Certain vertebrae from the Greensand of New Jersey, North 

 America, submitted to my examination by Prof. Henry Rogers, 

 in 1849 f, presented mosasauroid characters, but differed from 

 those which had been referred by Cuvier % and Goldfuss§ to 

 the type genus Mosasaurus in a degree which led me to re- 

 mark that " they might belong to the genus Leiodon ;" but 

 I, provisionally, described and figured them under the name 

 of " Macrosaurus Icevis." Similar vertebras were subse- 

 quently discovered by Prof. Emmons in Cretaceous deposits 

 of North Carolina, and were referred by him to the genus 

 Macrosaurus ||. 



Dr. Joseph Leidy, in his excellent work l On the Cretace- 

 ous Reptiles of the United States,' 4to, 1864, notices mosa- 

 sauroid teeth from other localities in the United States, several 

 of which he states to " correspond in all anatomical characters 

 with the teeth described by Prof. Owen as characteristic of a 

 distinct genus, to which he has given the name of Leiodon' 1 ' 1 \ ; 

 but in the figures of his plate xi. those teeth are referred to 

 Mosasaurus. 



Prof. E. D. Cope, in his richly illustrated volume on the 

 Vertebrata of the Cretaceous Formations of the West,- de- 

 scribes and figures specimens which enabled him to show that 

 the vertebras of Macrosaurus were actually those of Leiodon 

 Io3vis, and also to define other species of that mosasauroid 

 genus** obtained from the " Kansas chalk." 



Finally, in the ' Transactions of the Kansas Academy of 

 Science ' for 1877-8, vol. vi., Prof. F. H. Snow describes and 

 figures characteristic portions of an almost entire skeleton of 

 a Leiodon which he had the good fortune to expose in the 



* Report of the British Association for the Advancement of Science 

 for 1841, 8vo, p. 144. 



t Quarterly Journal of the Geological Society of London, vol. v. 

 (1849), p. 380, pi. v. 



\ Recherches sur les Ossemens Fossiles, 4to, 1824, tome v. 2 e partie. 

 p. 310. 



§ Nov. Act. Acad. Nat.-Cur. vol. xxi. p. 179 (1845). 



|| Report on the Geology of North Carolina, 1858, p. 213, fig. 34, a. 



% Smithsonian Contributions to Knowledge, vol. ut supra, p. 130. 



** "Several names have been proposed for our species, the earliest of 

 which is Macrosaurus, Owen. This name applies to species with com- 

 pressed dorsal vertebrae, as L. lavis and L. Mitchellii, both from New 

 Jersey Greensand." — Section "Leiodon, Owen," op. cit. 4to, 1875, 

 pp. 160, 161, pis. xxviii.-xxxiii. 



