NOTODIAPHORUS CRASSUS 37 



the plantar side are the most marked features. The 

 ectal facet is in two planes, the anterior portion being 

 bent down to nearly right angles with the 

 posterior, which seems to be characteristic 

 of this Diadiaphorus series. The susten- 

 tacular facet also is characteristic, being 

 gently rounded and extending clear to the 

 navicular facet on the head, in Diadia- 

 phorus becoming actually confluent with 



1 ° J Fig. ii. Left astragulus 



the navicular facet. Just at the edge of P lan . tar si t de: ?• . ecta ' facet 



J B — i/2jiatural size; b, sus- 



this sustentacular facet is a tiny surface j^i|S3d. facet: c,facet 

 where the astragulus rubs on the cuboid, 

 the only case, as far as I am aware, where this occurs in 

 any Litopterna. 



The calcaneum is long and slender, the tuber being but 

 slightly enlarged, its sustentacular facet being a broad 

 oval surface, while the ectal facet is in two planes to cor- 

 respond to that on the astragulus. The facet for the cuboid 

 is at the distal end, but is unusually oblique, its inner 

 margin sloping up almost to the sustentacular facet. It 

 is this slope which brings the cuboid in contact with the 

 astragulus. 



The navicular is broad and low, with a prominent hook 

 behind. On its upper face there is only the broad facet 

 for the astragulus head; on the lower face are three facets, 

 externally, a large, more or less triangular area, for the 

 ectocuneiform; medianly a smaller similar facet for the 

 mesocuneiform; and on the internal side, sloping up onto 

 the internal face, a small facet for the reduced endocunei- 

 form. On the external face of this bone there is a tiny 

 beveled facet for the cuboid. 



The endocuneiform is a large scale-like ossicle articulating 

 on the lateral internal face of the navicular, and over- 

 lapping markedly the inner surface of Metatarsus II. 



The mesocuneiform is considerably reduced in size, 

 carrying a broad flat facet on the upper surface for the 



