32 E. B. BRANSON 



Deltodus spatulatus Newberry and Worthen, 1870 {ibid., Vol. IV, Plate III, 



Fig. 11). 

 Cochliodus costatus (pars) Newberry and Worthen, 1870 (ibid., p. 364, Plate III, 



Fig. 12 [not Fig. 10]). 

 Deltodus spatulatus Newberry, 1879 (Annual Report of the Geological Survey of 



Indiana, p. 346) 

 Deltodopsis? convolutus St. John and Worthen, 1883 (Paleontology of Illinois, 



Vol. VII, p. 165, Plate XI, Figs, n and 12). 

 Cochliodus costatus (pars) St. John and Worthen (ibid., p. 167). 

 Deltodus latior St. John and Worthen (ibid., p. 145, Plate IX, Figs. 11 and 12). 

 Deltodus spatulatus Newberry, 1897 (Transactions of the New York Academy of 



Science, Vol. XVP p. 292, Plate XXIX, Figs. 8-11). 

 Deltodus spatulatus Eastman, 1903 (Bulletin of the Museum- of Comparative 



Zoology at Harvard College, Vol. XXXIX, Plate IV, Figs. 41 and 42; Plate 



V, Fig. 55). 



In the collection of Walker Museum are several nearly perfect 

 specimens of Deltodus spatulatus teeth from the Keokuk lime- 

 stone, and a large number of more or less complete specimens from 

 the Burlington limestone. Those from the Keokuk are generally 

 much better preserved than the ones from the Burlington. On 

 the Keokuk specimens a few lines of growth are usually present, 

 but the Burlington specimens rarely have lines of growth developed. 

 One specimen from the Keokuk is remarkable for the great develop- 

 ment of the outer end of the tooth. It curves downward and back- 

 ward, lacking about ioo° of forming a complete circle. From the 

 fact that this curved part is very slender, and consequently would 

 rarely be preserved, it is possible that it was generally developed 

 to a much greater degree than has formerly been supposed. The 

 complete outer end or antero-lateral margin has not been observed 

 in any of the teeth from the Burlington limestone. 



A study of these specimens substantiates Eastman's view 1 that 

 Deltodopsis ? convolutus 2 , and the narrow, strongly enrolled teeth 

 called by Newberry and Worthen Cochliodus costatus 5 are probably 

 the median or anterior teeth of Deltodus spatulatus. A great many 



1 Bulletin of the Museum of Comparative Zoology at Harvard College, Vol. XXXIX, 

 p. 199. 



2 St. John and Worthen, Paleontology of Illinois, Vol. VII, p. 165, Plate XI, Figs" 

 11 and 12. 



3 Ibid., Vol. II, p. 364, Plate III, Fig. 12 ? (not. Fig. 10). 



