76 



BtTLLETIN 89, UNITED STATES NATIONAL MUSEUM. 



homologous element in the Elephas foot. It probably represents the articulation 

 for the much reduced and last phalanx of this digit. 



The principal measurements of these bones are as follows: 



Greatest transverse diameter 



Greatest anteroposterior diameter. 

 Greatest depth of posterior face 



Proximal phalanges 

 No. 4934. 



Digit in. 



44 

 19 

 27 



Digit JV. 



mm. 

 137 



Of the other phalanges found associated with disarticulated feet, they appear 

 intermediate in form and deserve no especial mention. The fore foot is provided 

 with at least two flattened unguals, and though as yet not found articulated, un- 

 doubtedly belong to digits I and II. 



2 



,iIIL 





Fig. 41.— Dorsal view of unguals of Stegosaurus. 1, Ungual of hind foot. Cat. no. 7419, U.S.N.M. Juvenile 

 2, Ungual of digit I, fore foot. Cat. no. 4937, U.S.N.M. Type of Stegosaurus sulcatus Marsh. 3, Ungual of 

 digit I, fore foot. Cat. No. 7401, U.S.N.M. Juvenile. All figures h nat. size. 



These unguals are flattened, hoof-like bones that during the life of the animal 

 were doubtless incased in a horny nail. The specimens with which two unguals 

 have been found show that they are of two styles, one of which is as broad as long, 

 the other more elongated. The relative shape and size of these unguals are well 

 shown in figure 41. From the position in the rock of the elements pertaining to 

 the right fore foot of No. 4934, I am led to believe that the elongated ungual (1, 

 fig. 41) belongs to digit I. 



In old individuals the surfaces of these bones become very much roughened, 

 and the lateral, posteriorly directed points shown in figure 41, 1 and 3, continue 

 to ossify until they project posterior to the articular end as blunt rounded points 

 (fig. 41, 2). 



Belonging to the fore foot of No. 7401 are other elemerits which from their 

 close resemblance to some of the reduced terminal phalanges of Elephas are con- 

 sidered the final ones of the remaining digits. Antero-posteriorly these are very 



