NOTES ON THE CANIDJ3 OF THE WHITE RIVER OLIGOCENE. 39*3 



toward the fibular side of the foot, making the tibial border somewhat concave. The 

 length of the bone, as already intimated, is not determinable, but the portion preserved 

 in one specimen is nearly as long as the entire fifth metacarpal of the same individual. 



The second metatarsal is much stouter than the first and more slender than the 

 third. The head is very narrow, being slightly excavated on the tibial side. Owing to 

 the shortness of the mesocuneiform, the head of mt. ii rises above the level of rut. i 

 and iii and is firmly held between the ento- and ectocuneiforms, though there are no such 

 distinct lateral facets for these tarsals as we find in Cards ; a stout prominence occupies 

 the plantar side of the head. The shaft is slender and of oval section, not having 

 acquired the trihedral shape characteristic of the recent dogs. 



The third metatarsal is the stoutest of the series ; the head is broad dorsally but 

 very narrow on the plantar side, where there is a large, projecting process, more promi- 

 nent than in Canis. The facet for the ectocuneiform is convex (in the recent dogs it is 

 slightly concave) and oblique in position, inclining downward toward the tibial side. 

 Deep sulci iuvade the head on both sides ; on the tibial side the sulcus is narrow, but 

 that on the fibular side is broad. A deep pit on the fibular side of the head receives a 

 corresponding prominence from mt. iv, and an additional facet for the same metatarsal is 

 found on the plantar projection, so that the two median metatarsals are very firmly inter- 

 locked. The shaft, for most of its length, is of transversely oval section, very different 

 from the squared, prismatic shape seen in Canis, though an approximation to this shape 

 occurs in the proximal portion of the shaft, where mt. iii and iv are closely appressed. 

 The distal end is broadened and antero-posteriorly compressed ; the trochlea resembles 

 that of the corresponding metacarpal, save that it is larger and relatively somewhat 

 lower. 



The fourth metatarsal is of nearly the same thickness as mt. iii, though a trifle 

 more slender. The head is narrow and the facet for the cuboid is slightly convex in 

 both directions; the plantar extension is neither so broad nor so prominent as in Canis. 

 On the tibial side is a rounded protuberance, which is received into the depression 

 already mentioned, in the head of mt. iii, while on the fibular side is an excavation for a 

 prominence on mt. v, and proximal to this excavation is a narrow but well-defined facet 

 for the same metatarsal. Very little of the shaft is preserved, and this proximal por- 

 tion has much the same tetrahedral shape as in the recent dogs. Doubtless, however, 

 the distal part of the shaft assumes a transversely oval section, as does that of mt. iii, 

 though the digits of the pes evidently diverge less distally than do those of the manus. 



The fifth metatarsal is entirely missing from all of the specimens, so that the inter- 

 esting question regarding the reduction of the external ascending process cannot be 

 answered. 



