106 IOWA GEOLOGICAL SURVEY 



Phoebodus politus Newberry. 

 (Plate I, Fig. 9) 



1889. Phoebodus politus J. S. Newberry, Monogr. U. S. Geol. Surv. 16, p. 173, 



pi. 27, figs. 27-28a. 

 1899. Phoebodus politus C. R. Eastman, Journ. Geol. 7, p. 491, pi. 7, fig. 5. 

 1907. Phoebodus politus C. R. Eastman, Mem. N. Y. State Mus. 10, p. 60, pi. 1, 



fig. 12. 



Newberry's description of this rare and interesting form is as 

 follows : 



Teeth small, robust, breadth between tips of lateral cusps 6 

 to 12 mm, height from 4 to 8 mm, base broadly elliptical, thick, 

 with a broad bilobed, padlike prominence in the middle portion 

 of the upper surface, concave below, with a narrow arch between 

 the cusps; cusps three, of nearly equal size, with minute rudi- 

 mentary ones in the angles between them, all strongly recurved, 

 flattened in front with salient, acute angles, rounded behind; 

 surface smooth and polished, or bearing a few short, coarse 

 striations. 



The relations of this species have been commonly supposed 

 to be with Cladodus, rather than with Diplodus, but recent dis- 

 coveries of more perfect examples which display the characters 

 of the root in this and other species leave no doubt as to the 

 Pleuraeanthid nature of these teeth. An illustration is given in 

 Plate I Fig. 9 of one of the most perfect specimens of P. politus 

 that have yet been obtained. The original is preserved in the 

 Museum of Comparative Zoology at Cambridge, Mass., and is 

 from the Cleveland shale of Lorain county, Ohio. 



Formation and locality. Cleveland shale (Upper Devonian) ; 

 Ohio. 



Phoebodus macisaacsii St. John and Worthen. 



1875. Bathycheilodus macisaacsii St. John and Worthen, Pal. Illinois, 6, p. 



252, pi. 1, figs, lm, 13. 

 1889. Phoebodus macisaacsii A. S. Woodward, Cat. Foss. Fishes British Mus. 



part 1, p. 27. 



A much smaller species than the preceding, and distinguished 

 from it by its relatively elongated base and more extensively 

 striated coronal surface. Length of base not exceeding 3 mm, and 

 total height less than 1.5 mm. A pair of low, obtuse and striated 



