AKTIOUACTYLA. 
327 
oped. The hemispheres are well convoluted, the longitudinal posterior 
convolutions giving way anteriorly to lobulate ones. The Sylvian fissure 
is Avell marked. The sides of the medulla oblongata are compressed and 
vertical at the pons, in correspondence with the vertical position of the pet¬ 
rous bones. The origins of the ophthalmic and maxillary branches of the 
trigeminus nerve are not divided by a septum, while that of the mandibular 
branch is quite distinct from the others. The optic nerves are large. The 
olfactory lobes are separated by a deep fissure below the extremity of the 
hemispheres; they project freely beyond the latter, being sejjarated by a 
deep fissure. Their free portions are short, truncate, and compressed. The 
anterior pyramids are not preserved on the inferior face of the cast of the 
medulla oblongata. The hippocampal lobes are subround and protuberant. 
From the description given under the head of the P. occidentalism it may 
be derived, that while the arrangement of the convolutions of the anterior 
lobes of the hemispheres is more simple than in any recent Ruminant, that 
of the middle and posterior lobes is essentially similar to that characteristic 
of the latter order of Mammalia * * 
A number of specimens of individuals of this genus were obtained, 
which are referable to two species, a smaller and a larger. Still larger 
individuals may be referable to a third species of the genus, or to the Pli- 
aiiclienia vulcanorunim whose teeth occur in the same localities. Three spe¬ 
cies, having similar relations of size, were originally described by Dr. 
Leidy, from Nebraska, under the names of P. gracilis, P. occidentalism and 
P. rohustusm and the first tw’o are probably those found in the Santa Fd 
marls. In the corresponding horizon in Colorado, the proportions of the 
jaws and teeth of the Procameli obtained do not coincide with those of the 
sjDecies named by Dr. Leidy, one being intermediate in size between the P. 
gracilis and the P. occidentalism and another intermediate between the latter and 
the P. rohustus. The first I identified provisionally with the P. occidentalism 
but I believe it to be distinct, and name it P. fissidens.\ The second species 
is the P. angustidenSm Cope. 
*See Paul Gervais, Journal de Zoologio, i, 1872, p. 459. 
* Procamelus fissidensm Cope {? F. occidentalism “ Leidy ”, Cope Aun. Eept. U. S. 
Geol. Surv. Terrs., 1873, p. 531).—This species is distinguished by the shortening of 
the series of true molar teeth as compared with the premolars; I'or, while the secoud, 
third, and fourth premolars are similar in dimensions to those of the P. occidentalism 
