NOTES ON THE'CANID.E OF THE WHITE RIVER OLIGOCENE. '■'>')■') 



The mesocuneiform is a very small, wedge-shaped bone, broadest dorsally and thin- 

 ning to an edge on the plantar side. The navicular facet is concave and very different 

 from the curious oblique surface which we find in Dinictis. As is well-nigh universal 

 among the Carnivora, the proximo-distal diameter of this bone is much less than that of 

 either of the two adjoining cuneiforms, an arrangement which allows the head of the 

 fourth metatarsal to rise above the level of the first and third. 



The ectocuneiform is, as usual, much the largest of the three, though it is not so 

 large proportionately as in Dinictis. The shape of this element is very much as we find 

 it in Canis, but with certain minor differences. Thus, the proximal end is less extended 

 in the dorso-plantar diameter, and the navicular facet is more concave ; the plantar 

 tubercle has a more constricted neck and enlarged, rugose head ; the facets on the tibial 

 side for the mesocuneiform and second metatarsal, and on the fibular side the inferior 

 facet for the cuboid are more distinctly developed, while the distal facet for mt. iii is more 

 concave and has a shorter plantar prolongation. 



As a whole, the character of the tarsus is rather more machairodont, or viverrine, 

 than canine. A conspicuous difference from the tarsus of the modern Canidce. is to be 

 seen in the fact, that the articulations which in the latter are nearly plane (e. g., the 

 cubo-calcaneal) in Daphcenus retain their more primitive concavo-convexity. 



The metatarsus consists of five members, which are longer and relatively more 

 slender than the metacarpals, though an exact comparison between the two cannot yet be 

 made, because the collection contains no specimens in which both metacarpals and meta- 

 tarsals are represented by anything more than fragments. 



The ji?°st metatarsal is considerably longer and stouter than tile corresponding meta- 

 carpal. In this case we can determine the true proportions, for of the species to which 

 the finely preserved hind foot (PI. XX, Fig. 21) belongs, D. hartshornianus, we also 

 possess a pollex, though associated with a different specimen. The almost exactly similar 

 skulls of the two individuals show that the animals were of approximately equal size. 

 The head of mt. i is enlarged in both the transverse and dorso-plantar diameters, and bears 

 a roughened tubercle upon the plantar side. The proximal facet, for the entocuneiform, 

 is large, and strongly convex antero-posteriorly, nearly plane transversely ; no other 

 facets are visible on the proximal end. The shaft is slender and arched toward the dorsal 

 side ; in section it is transversely oval, expanding somewhat at the distal end, where the 

 breadth is increased by the prominent tubercles for the lateral ligaments. The distal 

 trochlea is small, but well developed, and of irregularly spheroidal shape, with plantar 

 carina. The first metatarsal of Dinictis is like that of Daphcenus, and certain viverrines, 

 such as Gynogale, also have a hallux of much the same proportions, but in all the 

 recent Canidas, with the exception of certain domesticated breeds, mt. i is reduced to a 

 nodule. 



