198 IOWA GEOLOGICAL SURVEY 



merical abundance, is the Hydraulic limestone (Hamilton) of 

 Milwaukee, Wisconsin. Characteristic remains occur in the New 

 Albany ( = Grenesee) Black Shale near Louisville, Kentucky, and 

 also in the Oneonta beds (Senecan) near Delphi and Oxford, New 

 York. 



Dinichthys newberryi Clarke. 



1885. Dinichthys newberryi J. M. Clarke, Bull. U. S. Geol. Surv. no. 16, p. 



17, pi. 1, fig. 1. 

 1889. Dinichthys newberryi J. S. Newberry, Monogr. U. S. Geol. Surv. 16, p. 



153. 

 1897. Dinichthys newberryi C. R. Eastman, Bull. Mus. Comp. Zool- 31. p. 30, 



pi. 1, fig. 2. 



1906. Dinichthys newberryi L. Hussakof, Mem. Amer. Mus. Nat. Hist. 9, p. 



145. 



1907. Dinichthys newberryi C. R. Eastman, Mem. N. Y. State Mus. 10, p. 



133, pi. 6, fig. 2. 



Mandibles attaining a total length of 28% cm in the type speci- 

 men, with very prominent anterior beak, simple trenchant mar- 

 gin, and closely resembling that of D. pustulosus in general out- 

 line. There are, however, no denticulations or tubercles along 

 the downward slope immediately behind the cutting margin, and 

 the other plates associated with the type specimen have a 

 smooth external surface. 



A single dorsomedian plate from the same horizon as the type, 

 and considered by Dr. Clarke to be specifically identical with it, 

 is thus described by him : 



"In the same Styliola layer as it outcrops on the east side of 

 Canandaigua like, near Grenundewah, 6 miles from the Bristol 

 locality, I had earlier discovered a dorsomedian plate belong- 

 ing presumably to the same species. Its dimensions are as fol- 

 lows: length, 12y 2 cm (broken); width anteriorly, 1334 cm; 

 height of carinal process, 5 cm. . . . The posterior edge of 

 this plate in D. newberryi is broken and has apparently lost 3 or 

 4 cm from its length. The smallness of the bones of D. netr- 

 berryi does not indicate immature growth of an individual of 

 either of the other species [i. e., D. terrelli or D. lierzeri] . The 

 discovery in outcrops of the same horizon, in localities sep- 

 arated by a distance of several miles, of bones of different 

 individuals, all of which seem to agree with one another in their 

 relative proportions, is at least presumptive evidence that these 

 individuals had attained maturity and that the size of the bones 

 given above is that of normal full growth." 



