EASTMAN: CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 197 



1883. Sandalodus laevissimus St. John and Wortheii, Pal. Illinois, Vol. VII., p. 186, 



PI. XII., Figs. 8, 9 (and 5?). 

 1897. Deltodus grandis J. S. Newberry, Trans. N. Y. Acad. Sci., Vol. XVI., p. 297. 

 1900. Sandalodus laevissimus C. R. Eastman, Anier. Nat., Vol. XXXIV., p. 581, 



Fig. 1. 

 1902. Sandalodus laevissimus 0. H. St. John, Amer. Nat., Vol. XXXVI., p. 659. 



This species is very abaudaut in the Keokuk limestone of Iowa, Illinois, and 

 Missouri, numerous perfect examples being known of both the posterior and 

 anterior dental plates of upper and lower jaws. 

 Most of the posterior dental plates have suffered 

 the loss of the initial coiled portion, which is re- 

 markable for being wound upon itself one and 

 one-half times before expanding into the func- 

 tional grinding surface characterizing the adult, 

 as shown in the adjoining text-figure. The upper 

 posterior dental plate resembles in a general way 

 that of S. morrisii Davis, and is much less pli- 

 cated than the lower. There can be no doubt 

 as to the correctness of St. John and Worthen's 

 conclusion that the type of Deltodas grandis 

 Newb. and Worth, is identical with this species, 

 hence we are unable to agree with the views 

 expressed on this subject in the posthumous paper 

 of Newberry. 1 



Dr. 0. P. Hay is evidently mi.staken in his 

 remark that no type of the genus Sandalodus 

 has been specified,"'^ for »S'. laevissimus is expressly 

 designated as such by St. John and Worthen in 

 their general observations on teeth of this form.^ 

 Dr. Hay is also in error, we believe, when he 

 discards the specific title of .S. laevissimus in 

 favor of S. crass us. But possibly this may be 

 due to an oversight on his part, since the 

 original description of S. laevissimus with its -p^^ -^-^ 



accompanying illustrations - that which heads. ^„„^„;,^„,, ,„,,,-,,,•,„„, n. and 

 the list m the above synonymy — is omitted ^^ Keokuk limestone, 

 by him in his citations of the literature Keokuk, Iowa. Posterior 

 references.* dental plate of left man- 



dibular ramus, X f- 



1 Trans. N. Y. Acad. Sci., Vol. XVI., 897, p. 297. 



- Bibliography and Catalogue of the Fossil Vertebrata of North America. 

 Bull. U. S. Geol. Surv., No. 179 (1902), p. 288. 



3 Pal. Illinois, Vol. VII. (1883), p. 184. 



4 Lot: cit., p. 289. 



