EASTMAN: CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 197 
1888. Sandalodus laevissimus St. John and Worthen, Pal. Illinois, Vol. VII., p. 186, 
Pl. XII., Figs. 8, 9 (and 5%). 
1897. Deltodus grandis J. S. Newberry, Trans. N. Y. Acad. Sci., Vol. XVL, p. 297. 
1900. Sandalodus laevissimus C. R. Eastman, Amer. 
Fig. 1. 
Nat., Vol. XXXIV., p. 581, 
1902. Sandalodus laevissimus O. H. St. John, Amer. Nat., Vol. XXXVL, p. 659. 
This species is very abundant 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 Deltodus 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.! 
Dr. O. P. Hay is evidently mistaken 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. crassus. But possibly this may be 
due to an oversight on his part, since the 
original description of S. laevissimus with its 
accompanying illustrations —that which heads 
the list in the above synonymy —is omitted 
by him in his citations of the literature 
references.4 
1 Trans. N.. Y: Acad. Sci., Vol. X VI., 897, p. 297. 
Bigs li 
Sandalodus laevissimus N. and 
W. Keokuk limestone, 
Keokuk, Iowa. Posterior 
dental plate of left man- 
dibular ramus, X 2. 
2 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. 
* Loc. cit., p. 289. 
