1903] Lower Jaw of Dryptosaurus inxrassatus. 139 



Combined thickness of dentary and surangfular at //, figure 3 10 



Leng-th of crown of fifth tooth of right ramus 54 



Breadth of base of crown of same 28 



Thickness of ,, ,, 18 



Of smaller specimen, collected in 1889 (plate II). 



Length of dentary, above, to its junction with the surangular 380 



Depth of dentary at its junction with the surangular 160 



Length of angular foramen , 50 



Length of crown of sixth tooth 38 



Breadth of crown of same at base 18 



Length of crown of seventh tooth 55 



Breadth of crown of same at base 21 



Length of crown of eighth tooth . 46 



Breadth of crown of same at base 21 



Length of splenial foramen 52 



Explanation of plates of figures illustrating the mandible of 

 Dryptosaurus inctassatus (Cope). 

 Plate I. 

 Figure i. Mandible of the larger of the two specimens, as seen from the left; 

 two-fifteenths, or slightly more than one-eighth, the natural 

 size. 

 Figure rA. Section of left ramus of same, through the sixth tooth from the 

 front ; similarly reduced. 



Plate II. 

 Figure 2. Side view of mandible of specimen collected in 1889 ; one-sixth 



natural size. 

 Figure 3. Exterior aspect of posterior end of left ramus of mandible shewn 



in plate I ; one-fourth natural size. 

 Figure 4. Interior view of same ; similarly reduced. 



Plate III. 



Figure 5. Exterior of left ramus. 



Figure 6. Interior of the same. 



Figure 7. Outlines of transverse sections of a tooth; the upper section is 

 taken at about one-third the height of the crown below its 

 apex ; the middle section from a little below the mid-height of 

 the crown ; the lowest section from near the base of the 

 crown ; in the figures the upper side corresponds with the 

 outer surface of the tooth and the portions on the right to the 

 anterior border of the crown. 



d, dentary ; ang., angular ; art., articular ; sur,, surangular ; sp., 

 splenial ; psp., presplenial ; cor., coronoid. 



