EDENTATA OF THE SANTA CRUZ BEDS. 203 



facet for the ectocuneiform meet at an obtuse angle and on the fibular 

 side of the head is a very large plane surface for the fourth metatarsal ; 

 the broad distal trochlea has a very prominent and thick carina, which, 

 however, does not attain such proportions as in Megalonyx. 



Metatarsal IV is in very striking contrast to III, being more than twice 

 as long and very much more slender; it is relatively longer, straighter 

 and of more regular shape than in Megalonyx and has more nearly the 

 proportions of Nothrotherium ; the proximal end is narrow and of great 

 dorso-plantar thickness and bears an oblique facet for the cuboid, and 

 extensive lateral facets for the adjacent metatarsals, and the relative posi- 

 tion of these three facets is such that the bone is given a strongly diverg- 

 ent direction, as in Nothrotheriiim ; the shaft is relatively slender and 

 elongate, almost straight and of subquadrate section with rounded angles ; 

 the trochlea is narrow, not much wider than the shaft, but very thick and 

 with very prominent carina. 



Metatarsal V has much the same characteristics as in Nothrotherium 

 and Megalonyx ; the cuboid facet is very much narrower than in those 

 genera, especially the latter ; the shaft is depressed and shorter than that 

 of IV and gives off from the fibular side near the proximal end a very 

 large, triangular process, which is unfortunately broken, but was doubtless 

 shaped as in other species of Hapalops and very similar to that of Nothro- 

 thermm; the distal trochlea is quite different from that of II, III and IV, 

 being merely an elliptical convexity, without carina. 



The phalanges are very much like those of the manus, but considerably 

 shorter, and those of digits II and III are much heavier. The first pha- 

 lanx of the hallux is relatively long, laterally compressed and slender; its 

 proximal trochlea is deeply concave and but feebly grooved for the carina ; 

 near the distal end is a deep dorsal pit to receive the beak of the ungual. 

 In digit II the first phalanx is short, wide and very thick, especially at the 

 proximal end, and both trochleae are very deeply grooved in the median 

 line, while in digit IV it is of nearly the same size as in II. All the 

 phalanges of the fifth digit have been lost. 



The second phalanx is like that of the manus in form, but in digits 

 II and III, at least, it is very much heavier. In the second digit 

 this phalanx is moderately elongate, though attaining no such length 

 as it has in Nothrotherium, and in the third it is very short and ex- 

 tremely heavy. 



