174 0. 0. Marsh — Notes on Mesozoic Vertebrate Fossils. 



The tooth from the Laramie described by Cope in 1882 as 

 a mammalian premolar and as the type of the generic name 

 Meniscoessus evidently belongs to the above or an allied genus, 

 and all three are unquestionably the teeth of Dinosaurian 

 reptiles pertaining to the order Stegosauria. On Plate IV, 

 figure 1, a very small but typical tooth of Stegosaurus from 

 the Jurassic is represented. The allied genus Diraeodon, also 

 Jurassic, has similar teeth. 



Aublysodon, Leidy, 1888. 



In the same publications above cited, Dr. Leidy also described 

 and figured, under the name Deinodon, a number of teeth 

 which he regarded as pertaining to carnivorous Dinosaurs, but 

 later, in 1868, he made a new genus, Aublysodon, for some of 

 these teeth which differed materially in form from those known 

 to belong to such Dinosaurs.* The teeth regarded by Leidy 

 as characteristic of Aublysodon are represented in figures 

 35-45, Plate IX, of the Transactions above quoted, and the 

 best preserved tooth of this series, which Leidy suspected to 

 be an incisor, is shown in figures 41-45. The latter figures are 

 carefully reproduced on Plate III, figure 4, of the present 

 article, and two other similar teeth are represented on the 

 same plate. They all have the same characteristic chisel- 

 shaped crowns, covered with a thin coat of enamel, and show 

 indications of wear. 



The teeth referred by Leidy to the genus Aublysodon and 

 many others of the same general character since discovered 

 may be divided into the four following groups, all the speci- 

 mens of which appear to be somewhat curved either to the 

 right or left : 



(1) Large teeth (Leidy's figures 37-40) having both edges 

 crenulated, and the posterior ridge between them broad. The 

 wear of the apex is apparently posterior. 



(2) Somewhat smaller teeth, but still large, one of which is 

 represented in Plate III, figure 5. Faint crenulations may be 

 detected on the edges. The wear of the apex is on front and 

 back, and also on the side, probably the outside. The posterior 

 central ridge is narrow. This tooth represents a distinct species 

 which may be called Atiblysodon amplus. 



(3) Smaller teeth with no crenulations, and the posterior 

 ridge with a groove (Leidy's figures 41-45). The wear of the 

 apex is in front. These may be regarded as typical of 

 Aublysodon mirandus, Leidy. 



(4) The most abundant teeth are much smaller, with no 

 crenulations, and the posterior ridge sharp and not grooved. 



*Proc. Acad. Nat. Sci. Philadelphia, p. 198, 1868. 



