0. C. Marsh — New Genus of Sauropoda. 



93 



JPriconodon crassus, gen. et sp. nov«. 



The existence of another herbivorous Dinosaur in the same 

 horizon of the Potomac formation is indicated by a number of 

 fragmentary remains, the most characteristic of which is the 

 tooth figured below. This may be regarded as the type speci- 

 men. Although resembling somewhat the -teeth of Diracondon 

 from the Jurassic of the West, it is quite distinct. It has the 

 narrow neck, swollen base, and flattened crown of that genus, 

 but the serrated edges meet above at a sharp angle, instead of 

 forming a wide curve at the apex. 



Fig. 7. 



Fig. 8. 



Fig. 9. 



Figure 7. Tooth of Priconodon crassus, Marsh ; side view. 

 Figure 8. The same tooth; end view. 

 Figure 9. The same ; inside view. 



All the figures are twice natural size. 



The surface shown in figure 7 is much worn by the opposing 

 tooth. In figure 9, the pit formed by the succeeding tooth is 

 seen near the top of the fang. 



The other remains at present referred to this species were 

 not found with this tooth, and hence, their relations to it are 

 uncertain. They will be described more fully elsewhere. 



All the remains supposed to pertain to this animal are from 

 the Potomac formation, Prince George Co., Maryland. 



Allosaurus medius, sp. nov. 



Besides the herbivorous Dinosaurs described above, remains 

 of two carnivorous forms were secured from the same horizon. 

 The larger of these, which may be provisionally referred to the 

 genus Allosaurus, is represented by various specimens, the 

 most characteristic of which are teeth, and bones of the limbs 

 and feet. The teeth are remarkably flat and trenchant, with 

 the edges finely serrated, and the surfaces very smooth. The 

 limb bones, and even the phalanges, are unusually hollow, and 

 the latter have the articulations finely finished. The principal 

 dimensions of some of the parts preserved are as follows : 



One tooth has the crown 30 mm in height ; its anteroposte- 

 rior diameter at base 15 mm ; and its transverse diameter 7 mm . 



