330 
A MEMOIR UPON THE GENUS 
associated with the tibia, No. 10,357, already described. The measurements (jf tliis 
astragalus correspond very closely with those given by Leidy for this species. There 
is also another astragalus and calcanenm, No. 10,288 B, whose characters and 
measurements approximate closely to those above referred to. The foot in P. minor 
is narrower in comparison with its length than the foot of P. pahidosns. This 
is especially noticeable in the form of the calcanenm and astragalus, which are 
very much* lighter than in the larger species. The astragalus especially has the 
elongated form and rather slender neck so characteristic of that of Lmmohyops. Tlie 
size and proportions of the pes in this species are about the same as that of Tapirns 
indicus. The foot of the latter, however, is rather more elongated in pi’oportion to 
its breadth than that of P. minor. The arragement, form and larger size of the 
tarsal facets, together with the shape of the cuboid, distinguish the tarsus of this 
species from that of the larger species of Plyrachyus. 
Calcanenm . — The calcaneum is long and narrow ; its articular portion being 
much narrower than that of P. pa/tidosus. The distal portion of the tuberosity is 
wanting in this specimen but the basal portion of the same is preserved and is rather 
slender and compressed. The form of the calcaneal facets is nearly identical with 
that of the larger species ; the sustentacular is, however, longer and slenderer. 
The inferior and sustentacular facets approach each other nearer than in P. paln- 
dosus. The inferior facet is long and sharply separated from the cu)x)idal face of 
the bone. The cuboid facet is much nan-ower in compari.son with its ))readth than in 
the larger species ; it is more nearly horizontally placed than in the latter species- 
and slightly convex transvensely. (Juite a deep fossa separates the cuboid and the 
inferior facet from the sustentaculum. This calcaneum exhibits a well marked 
fibular facet. 
Astragahis . — The astragalus of P. minor is nearly as long as that of P. paludosus. 
but it is much narrower; its trochlear portion being about one-third less in extent 
than in the larger species. The distal part is much elongated and slender. The 
form of the trochleas is the same as in P. paludosus. but the height of the external 
trochlear is much less, and the isosterior portion of it thins out very much behind, 
thus allowing the sustentaculum to penetrate upwaixls more than in the larger 
species. The fossa spoken of as occupjdng the external trochlear face of the 
astragalus ot P. palndosns is only slightly marked. The most important difl’er- 
ence in respect to the facets of the inferior surface of the astragahis is that tlie 
sustentaculum and inferior facets are continuous. The ectal facet is very deep and 
narrow ; its anterior prolongation is not as great as in P. pahidosns. The susten- 
taculum is very long and nearly straight; its proximal end is separated from the ectal 
facet by an oblique fossa which runs across the surface of the bone. Anteriorly and 
mternally the sustentacidum is bordered by a prominent triangular ridge and the 
plane of the facet is oblicpie to it. A slight ridge is present at the junction 
of the sustentaculum with the cuboidal facet. The inferior facet of the astragalus 
IS narrow ; it terminates above and below by narrow extremities, its middle portion 
