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63 



UINTA SELENODONTS 



The metatarsus is composed, so far as is definitely known, of four func- 

 tional elements, for though the lateral pair are considerably reduced and are 

 more slender than the corresponding metacarpals, they are far from being 

 thread-like splints, such as we find in Protylopus. 



Metatarsal i. may, perhaps, have been preserved in the form of a ves- 

 tigial nodule, as is suggested by the facet on the distal end of the ento- 

 cuneiform. 



Metatarsal ii. is quite long and very slender; it is longer in proportion to 

 the median pair than is the second metacarpal, and much more slender. But 

 it must be borne in mind that the manus and pes here described belong to 

 different individuals, possibly even to different genera, although the example 

 of Leptomeryx, Prctoccras, and Protylopus shows that such a difference in the 

 degree of reduction between the fore- and hind-foot is not of itself unlikely. 

 The head of mt. ii. is slightly widened and thickened, and its plantar edge is 

 bevelled for the ento-cuneiform ; the shaft is slender and nearly straight. The 

 distal trochlea is very narrow, but has a considerable dorso-plantar thickness 

 and bears a prominent carina. 



Metatarsal iii. far exceeds mt. ii. in all of its dimensions, but is both 

 absolutely and relatively very much shorter than in Protylopus. It is consid- 

 erably longer and stouter than the corresponding metacarpal, though the 

 difference is less than in the last-named genus or in Leptomeryx. The proxi- 

 mal end is narrow, the shaft moderately long and stout, straight, and of nearly 

 uniform width throughout. For part of its length the shaft is trihedral, the 

 fibular side being flattened by its close approximation to mt. iv., assuming a 

 transversely oval section below. The distal trochlea resembles that of Proty- 

 lopus, being low and subspheroidal in shape rather than cylindrical ; it is 

 demarcated from the shaft by a somewhat deeper depression than in the 

 latter genus. 



Metatarsal iv. is slightly longer than mt. iii., its proximal and distal ends 

 standing at a little lower level than those of its fellow. 



Metatarsal v. corresponds in length and thickness to mt. ii., but has a 

 somewhat heavier and larger proximal end. 



Of the phalanges of the pes only a single one is preserved, a second 

 phalanx of one of the rnedian digits ; it closely resembles the corresponding 

 bone of Protylopus and is of nearly the same actual length. It is, therefore, 

 much longer in proportion to the length of the metapodials and decidedly 

 more slender. 



