414 Davis — On the Fossil Fish of the Cretaceous Formations of Scandinavia. 



Order.— HOLOCEPHALI. 



Family.— EDA P HOD NT ID iE, Owen. 



Genus. Ischyodus, Egerton. 



Ischyodus hrevirostris, Newton (Ag. MS.). 



(PI. XLii., figs. 12-15.) 



ChiniEera (Iscliyodon) brevirostris, Agassiz, L., 1843. " Poiss. Foss.," vol. iii., 



p. 344 (name only). 

 . Egerton, P. de M. Grey, 1843. " Proc. Geol. 



Soc," vol. iv., p. 156 (name only). 

 . Morris, J., 1854. "Cat. Brit. Foss.," 



p. 330. 

 . Newton, E. T., 1876. " Quart. Journ. Geo- 

 logical Soc." vol. xxxii., p. 326, pi. xxi., 



figs. 1—5. 

 . Newton, E. T., 1878. " Chimeeroid Fishes, 



Brit. Cret. Rocks (Mem. Geol. Survey)," 



p. 27, pi. IX. 

 . Davis, J. W., 1888. "Trans. Roy. Dubl. 



Soc," 2nd ser., vol. iv., p. 42. pi. vii., 



figs. 10-13. 



Ischyodus brevirostris, 

 Ischyodus brevirostris, 

 Ischyodus brevirostris, 



Ischyodus brevirostris, 



Ischyodus brevirostris. 



Several specimens of this Chimaeroid occur in collections from the Lund Uni- 

 versity. Mostly they are in a fragmentary condition. The specimen (fig. 12) is 

 an example of the left mandible, and the most perfect in the collection. The 

 posterior part of the jaw is defective and broken ; this is the case with all the 

 specimens, and has been explained by Newton. As the anterior parts of the jaws 

 are worn away, they are constantly pushed forward by the growth of new 

 matter behind, and the posterior parts always growing, and consequently being 

 imperfectly ossified, they are readily broken and damaged. The anterior margin 

 and the sinuous indentations which characterize it can be inferred, though the 

 margin is defective. The symphysial margin is slightly convex. The oval 

 surface of the tooth is divided between raised portions of dentinal substance and 



