368 The Ohio Naturalist. [Vol. VIII, No. 8, 



tinguished from the outer by heavier shading. The part that 

 projects forward beneath the suborbital is missing in all speci- 

 mens at the writer's disposal and is restored in the drawings 

 after Newberry^ and Hussakof.^ A part of the upper end is 

 restored in their specimen but is present in this one. In the 

 specimen under consideration there is no indication of a thick- 

 ened edge of the mandibular support. 



The arrangement of the supero-gnathals as near as can be 

 ascertained is the same as in Dinichthys ciirtus as figured by 

 Hussakof.^ Their exact relation to the suborbital is not clear, 

 though it is essentially that shown in figure 1. The anterior 

 end of the suborbital is complete on the left side but the postero- 

 supero-gnathal is missing. The anterior end of the suborbital 

 is missing from the right side. The notch in the anterior end 

 of the suborbital apparently fitted against some part of the 

 antero-supero-gnathal, but it is impossible to determine this fit 

 with the specimens at the writer's disposal. 



Placing the mandible in its natural relation to the supero- 

 gnathals it is found that the posterior end rests just beneath 

 the postero-infero-corner of the suborbital and against the inner 

 anterior projection of the clavicular. The conclusion that the 

 mandible rested against this projection is necessary. There is 

 no other bone which could furnish support for it. Hussakof 

 indicates this attachment in a general way in figure 1 of the paper 

 above cited. 



The slime canal on the marginal does not extend to the angle 

 of the marginal but branches to right and left as shown in figure 

 2. In other respects the canals do not differ materially from the 

 way they are represented by Hussakof in figure 24C of the paper 

 just cited. The shape of the skull differs considerably from 

 Hussakof 's restoration but agrees with Newberry's figures in 

 Plate IV, Monograph XVI, of the United States Geological 

 Survey . 



The dimensions of the bones following Hussakof's method 

 of measuring, are as follows: 



1. Monograph XVI, U. S. Geol. Surv., Plate XLVIII, figs. 1 and 2. 



2. Mem. Am. Mus. Nat. Hist., Vol. IX, Pt. Ill, p. 133, fig. 19. 



3. Mem. Am. Mus. Nat. Hist., Vol. IX, Pt. Ill, p. 112, fig. 5. 



