pisces. 127 



that it does not justify specific description. The extremes of variety are illustrated in 

 the following measurements of three adult specimens: Length 94 mm., 24 mm., 22 mm., 

 height 23 mm., 6 mm., 4 mm.; thickness 18 mm., 7 mm., 4 mm. The greater number 

 of specimens consist of only the worn tritoral parts. All of the large specimens are 

 from the Mineolaof Ralls County. Specimens are found, rarely, in the Callaway and 

 Snyder Creek. The species is most abundant in the basal Mississippian. 



Ptyctodas ferox Eastman 

 Plate 21, figure 12 



1898. Ptyctodus ferox Eastman, Amer. Nat. 32, pp. 480-484, text-figs. 35-40. 



1899. Ptyctodus ferox Eastman, Jour. Geol., 7, p. 282. 



1906. Ptyctodus sp., Dean, Carnegie Inst. Wash. Pub. No. 32, p. 139, text-fig. 126. 



1907. Ptyctodus ferox Eastman, Mem. N. Y. State Mus. 10, pp. 72-73. 



1908. Ptyctodus ferox Eastman, Iowa Geol. Surv., vol. XVIII, pp. 135-137, text-figs. 

 20-22. 



1911.. Ptyctodus ferox Cleland, Wisconsin Geol. Surv. Bull. 21, p. 151, pi. 49, figs. 



35-40. 

 1914. Ptyctodus ferox Branson, Devonian Fishes of Missouri, Missouri Univ. BulL, 

 Science Series, vol. 2, pp. 63-64, pi. 4, figs. 3 and 4. 



Description — A large species of the genus. The tritoral area of the upper jaw 

 terminates anteriorly in a slight prominence or tubercle situated somewhat nearer the 

 outside than the inside of the face and from this point outward as far as the crest of 

 the symphasis there is a beveling along the outer face where the beak of the lower jaw 

 played against it. Anteriorly, the upper dental plates project forward and upward in 

 a gently curved line, and they are bent inwardly toward the front. 



The lower dental plate is remarkable chiefly for its great height along the anterior 

 margin, general straightness, and strong prehensile beak. Superficially, it is marked by 

 fine concentric striae similar to those in Palaeomylus. 



Remarks — The different species of Ptyctodus are so variable and grade into each 

 other so remarkably that specific identification is uncertain. 



Occurrence — Snyder Creek shale of Callaway County. Only one specimen from 

 Missouri is known to the writer. 



Subclass Dipneusti 



Order Artlirodira 



Family Coccosteidae 



Genus Dinichthys Newberry 



Dinichthys pustulosus Eastman 



Plate 31, figures 7 and 8 



1897. Dinichthys pustulosus Eastman, Bull. Mus. Comp. Zool., 31, No. 2, p. 38, pi. 3 

 fig. 4. 



1898. Dinichthys pustulosus Eastman, Amer. Nat. 32, pp. 748-755, text-figs. 1 and 2. 



1900. Dinichthys pustulosus Eastman, Jour. Geol. 8, pp. 32-34, text-fig. 1. 



1901. Dinichthys pustulosus Dean, Mem. N. Y. Acad. Aci. 2, pt. 3, p. 122. 



1902. Dinichthys pustulosus Eastman, Amer. Nat. 36, p. 657, text-figs. 1 and 2. 



1906. Dinichthys pustulosus Hussakof, Mem. Amer. Mus. Nat. Hist. 9, pt. 3, pp. 

 142-148, text-fig. 22d. 



1907. Dinichthys pustulosus Eastman, Mem. N. Y. State Mus. 10, pp. 130-133, pi. 2, 

 fig. 6; pi. 5, figs. 2 and 3; pi. 12, text-fig. 25. 



