On some of the Characters of the Miocene Fauna of Oregon. (Read before the American Philosophical Society, November 15, 1878.) BY E. D. COPE. We have been for some time in possession of information as to the ungulate forms which inhabited Oregon during the Miocene period. Through the labors of Profs. Leidy, Marsh and Bettany, we have learned of the existence there of Oreodontida in considerable variety; of Anchitheriida; of peccary like species; of Elotherium, and of Rhinocerus. But of the unguiculate types, of Rodentia, and of the inferior orders of Mammalia, almost nothing is yet known. Having recently received a number of specimens from the deposits in question, I am in a position to offer a number of new identifications. The following species already known from the Miocene of Colorado, I find contained in the collection, viz.: Palaolagus haydeni; Canis gregarius; Canis lippincottianus; Hypertragulus calcaratus; Leptomeryx evansi. RODENTIA. STENEOFIBER GRADATUs, sp. nov. This species is represented in my collection by a cranium which is nearly perfect, the principal deficiency being the absence of the mandibular rami. It is of smaller size than the S. nebrascensis and S. pansus, and differs from both these species in the relative sizes of the superior molar teeth. The first of these is the largest, and the others diminish regularly in size to the last, whose grinding face does not present more than one-third the extent of that of the first. The triturating surfaces of the second and third have their long axes transverse. In all the crowns, besides the internal and external enamel inflections, there is but one fossette, which is anterior to the external inflection. The latter has become isolated from the superficial enamel on the last three molars, by attrition. The superior incisors are flat anteriorly with the external angle rounded, and its dentine presents the transverse undulations seen in S. pansus. From the above measurements it is apparent that the molar series in this species is equal in length to the anterior three molars of the S. nebrascensis antero-posterior.. .0020 .0024 and S. pansus. The posterior fossettes of the crowns seen in those species are wanting in the S. gradatus. ENTOPTYCHUS CAVIFRONS, gen. et sp. nov. Char. gen. Probably of the family Saccomyidæ.* The cranium is elongate, and presents inflated periotic bones, and slender zygoma. The foramen infraorbitale is small and anterior in position, entering the maxillary bone near its suture with the premaxillary. Generic characters. Molars 1-1, rootless, and identical in structure. The crowns are prismatic, and in the young stage present a deep inflection of enamel from one side, the external in the superior teeth, the internal in the inferior. After a little attrition, the connection with the external enamel layer disappears, and there remains a median transverse fossette, entirely enclosed by enamel. The tooth then consists of two dentinal columns in. one cylinder of enamel, separated by a transverse enamel-bordered tube. Incisors not sulcate. The teeth of this genus differ from those of Perognathus in being without distinct roots, and in having the enamel loop cut off and enclosed. In Dipodomys, the molars are undivided simple prisms. Specif. Char. This species is represented by some entire crania, and numerous separated jaws. The postorbital part of the skull is subquadrate in outline, and depressed in form. The interorbital region is narrowed, but the superciliary margins do not meet nor converge to form a sagittal crest. They are thickened, forming two subparallel ridges which are separated by a shallow concavity of the frontal bone. The nasal bones are very narrow, and their posterior apices just attain the line of the supero-anterior angle of the orbit. The base of the malar bone is much elevated and very oblique. The molar teeth are directed obliquely backwards, the alveolus of the first issuing below the anterior part of the orbit. The first superior molar is the largest, and the proportions of the others diminish regularly posteriorly. The first inferior molar is a little smaller than the second and third, and is about equal to the fourth. Its anterior column is contracted, while the last molar is like the second and third. The face of the inferior incisor is flat, and its enamel is smooth. The external face of the jaw is bounded below by a strong angle, as far anteriorly as below the first molar. *See Coues' Report U. S. Geol. Surv. Terrs. XI, p. 491. 1873.] [Cope. Width of crown of last molar...... ENTOPTYCHUS PLANIFRONS, sp. nov. .0015 .007 . .006 . .0016 A larger species than the E. cavifrons, represented in my collection by parts of crania, and rami. The former show that besides the superior size, this species differs from the E. cavifrons in the absence of the superciliary ridges, and hence perfect flatness of the interorbital region. The latter is also wider, measuring five-sixths the width of the muzzle at its middle, while in the E. cavifrons it is only half as wide. The subjoined measurements give the characters in detail. ENTOPTYCHUS CRASSIRAMIS, sp. nov. This, the largest species of the genus, appears to have been less abundant than the two already described. I refer to it portions of two crania and three mandibular rami, found separately. The superior size of the parts is obvious, the posterior three superior molars having the same longitudinal extent as the entire series of the E. cavifrons. The gradation in the size of these teeth, is as in that species, the grinding surfaces diminishing rapidly in extent posteriorly. The superciliary ridges are not well preserved, but were probably thickened as in E. cavifrons, and the interorbital space was relatively as narrow, and not so wide as in E.planifrons. The measurements below exhibit the characters more exactly. In the mandibular rami the inferior masseteric ridge extends to below the anterior border of the first molar, and is very prominent and acute. It results that both the exterior and inferior aspects of the ramus are con PROC. AMER. PHILOS. SOC. XVIII. 102. I. PRINTED DEC. 30, 1878. cave to the anterior extremity of the crest, which slopes upwards. The incisive alveolus, though not prominent as in the Hystricomorpha, is on the inner side of the base of the ramus in front, and the enamel-face of the incisor tooth is directed more inwards than downwards. Above the alveolar prominence, the inner face of the ramus is gently concave. The anterior origin of the coronoid process is opposite the posterior border of the second molar. PLEUROLICUS SULCIFRONS, gen. et sp. nov. Char. gen. Fam. Saccomydiæ. Superior molars rooted and short-crowned. The crowns with a lateral fissure bordered with an inflection of the enamel sheath, extending to their bases. In the superior molars this inflection is on the external side, and does not divide the crown. Superior incisors not grooved. This genus is curiously near to the existing Heteromys and Perognathus, the two genera of Saccomyide with rooted molars. The former differs in having the molars divided into two columns, each of which is sheathed in enamel, while Perognathus only differs so far as I am aware, in having the superior incisors grooved. Specif. Char. This species resembles those of the allied genus Entoptychus in many respects. The superciliary borders are thickened upwards, forming two ridges, which enclose a groove between them which is more pronounced than in the Entoptychus cavifrons. The muzzle is plane above and considerably wider than the interorbital space. The base of the malar is thin and oblique, and the foramen infraorbitale exterius is well in advance of the molar teeth and at the anterior part of the maxillary bone. A groove passes backwards from its inferior border, terminating in a small foramen which marks a point nearly half way to the first molar. Within this, another shallow groove bounds the more prominent median line. The palatal surface exhibits two shallow lateral grooves, which commence opposite the posterior border of the first molar. The grinding surfaces of the molars are transverse ovals, only interrupted by the exterior fissure. The first molar is slightly different in form, being larger, and its section, when not much worn, being nearly round. Its anterior portion extends towards the alveolus, giving an antero-posterior oval, on prolonged wear. Each tooth has three roots, one interior and two exterior; in the first they may be described as two posterior and one anterior. The last molar is the smallest, the series exhibiting a regular gradation in size. Interorbital width... Measurements. Width of muzzle at middle. M. .0050 .0080 MENISCOMYS HIPPODUS, gen. et sp. nov. Gen. Char. The characters of this genus are derived from the dentition of both jaws, and from portions of the cranium which are preserved. The molars are rooted, and number. Those of the superior series are without enamel inflections, and the triturating surface exhibits two external and one internal crescentic sections of the investing enamel. On the second superior molar there are three external crescents in the typical species; and the first molar is simply conic. Between the inner and external crescents, there are the curved edges of enamel plates directed obliquely and transversely. The grinding surfaces of the inferior molars display in the unworn condition, two L-shaped transverse crests, connected longitudinally on the median line; on wearing, the lateral emarginations of the enamel become shallower, disappearing from the inner side, but remaining on the outer. Incisor teeth not grooved. Foramen infraorbitale anterius, if present, elevated in position and near orbit. The characters of the dentition of this genus resemble those of the genus Pteromys, which is now confined to Asia and the Malaysian Archipelago. The superior molars differ from those of Pteromys in wanting all reëntrant enamel inflection. Specimens in my collection indicate two species of Meniscomys. Specif. Char. Superior molars with a vertical ridge from the points of junction of the crescents on the external side; there are thus two on the second molar, and one each on the third and fourth. Within each of the external crescents is another crescentic edge of a pair of vertical enamel plates, and the inner marginal crescent sends off. a short transverse branch towards them. With attrition, all these crests unite by their extremities, enclosing four distinct lakes, which, after still further wear, disappear. Attrition produces a similar result in the inferior molars, viz.: two pairs of crescents enclosing four lakes, which ultimately wear out. The inferior incisor has a shallow concavity on its anterior face. The maxillary bone, anterior to the molar teeth, is shorter than the premaxillary. The incisive foramina are entirely in the latter. The sides and superior aspect of the muzzle are regularly convex in transverse section. The inferior incisive alveolus is enclosed entirely in the plane of the ramus, and extends posteriorly to below the last molar tooth. The masseteric ridge is very oblique, and rises to a median point below the second molar. The coronoid process rises from the front of the last molar. Measurements. Length of superior molar series... M. .008 |