Part 26

Many of these extinct Lemuroids so combine the characters of the Insectivora and the Ungulata (or hoofed animals), with those of their own Sub-order, that it is often extremely difficult, even impossible, sometimes, to determine to which Order they really belong, owing to a blending of characters due to their common origin. The Upper Eocene forms present many affinities with the South American Capuchin Monkeys (Cebidæ). Dr. Forsyth Major is of opinion, however, that they are more highly, and not (as is generally believed) less specialised than those now living, which appear to have been the subject of retrogressive development.

The species to be noticed below are some of the more important of those which have been ascertained to belong to the present Sub-order.

No remains assignable with certainty to the families Chiromyidæ or Tarsiidæ, have as yet been discovered. The first form {112}to be mentioned belongs to a family which has now no living representatives.

FAMILY MEGALADAPIDÆ.

This family has recently been established by Dr. Forsyth Major, for a fossil species represented by the greater portion of a large cranium and part of its lower jaw, found in a marsh at Amboulisatra, on the south-west coast of Madagascar. This species is the only representative of the single genus of the family.

GENUS MEGALADAPIS.

Megaladapis, Forsyth Major, Phil. Trans., vol. 185 B, p. 15 (1894).

The cranium, about 10 inches long, indicates an aged animal three or four times as long as the common Cat, which is an enormous size as compared with any living Lemur. Brain-case straight, narrow, short, low, and situated at a higher level than the facial region; an enormous lateral development of the region between the eyes; orbits small in diameter, communicating freely with the temporal fossa, protruding outwards and forwards, and surrounded by a thickened ring; facial region elongate and bent upward; palate convex downwards from front to back; ridges for attachment of the temporal muscles uniting in a great central crest; frontal bones constricted behind the orbits; maxillary bones behind the molar teeth greatly inflated by air-cavities; the two halves of the lower jaw ossified together. In the upper jaw the pre-molars have one outer and one inner cusp, and the molars one internal and two external cusps, the former being deeply separated from the hind outer cusp, and joined by a ridge to the front outer cusp. In the lower {113}jaw, the posterior pre-molar has one outer cusp, a fore and hind inner cusp (each joined by a crescent to the outer cusp), and a central inner cusp; the three molars have two outer and three alternating inner cusps, and to the outer side a basal cingulum; the posterior molar has a strongly cusped heel.

MEGALADAPIS MADAGASCARIENSIS, Forsyth Major, the only species of the genus, presents many marsupial and insectivorous characters and features which show some approach towards the South-American Howlers (Alouatta), a specialisation "not in the least," according to Dr. Major, "implying a near relationship, but probably only an adaptation to a corresponding function" implied in the "vocal organs of unusual size," which, he believes, Megaladapis to have possessed. Lemurine characters, however, predominate. In the shape of its molars it is related to Lepidolemur, and still more closely to Microcebus and Chirogale, while by the characters of its inter-orbital region it approaches to the Sifakas (Propithecus) and the extinct Adapis.

The small diameter of its orbits suggests, according to Dr. Major, that in habits this extinct giant Lemur was diurnal; and from the conformation of its lower jaw "there exists," continues the same distinguished investigator, "a strong assumption that, as in Alouatta, it was provided with vocal organs of unusual size."

The age of this Howling Lemur, estimated either geologically or by years, cannot be of very great antiquity. Its remains were found associated with those of the giant Moa-like bird, the Æpyornis, of Tortoises and Hippopotami, all now extinct, and of Crocodiles still living in the interior lakes of the island. Some of these animals were certainly {114}contemporaneous with the now vanished Dodo and the large flightless Rail (Aphanapteryx), both of which were seen alive by Europeans little more than two centuries ago, and it is not improbable that Megaladapis may have been living in the Madagascar forests at the same period.

FAMILY LEMURIDÆ (anteà, p. 22).

In this family, and in its sub-family Lemurinæ (because of its affinities with Hapalemur), has to be included a large extinct species from Nossi Vey, in North-west Madagascar. Its fossil remains were recently described (P. Z. S., 1893, p. 532), but not named by Dr. Forsyth Major. They will prove, he believes, when more fully known, to be the type of a new genus. At present, however, owing to their incomplete state, it is not possible to describe the species fully. "The Lemuroid nature of the specimen is at once demonstrated by the great elevation and downward bending of the post-orbital processes ... showing that the osseous ring of the orbit was complete." Unusual for a Lemuroid is the very strong post-orbital constriction of the frontals, a character, however, seen in Adapis, an Eocene European form, and in Hapalemur. With the latter it agrees in the voluminous cranial and very short facial portion, and the "cuttingly sharp" inferior margin of its post-orbital process. Seen from the side, this fossil cranium is almost vertically truncated behind, as in the skull of Alouatta. The region between the eyes is vaulted by underlying air-chambers.

FAMILY ANAPTOMORPHIDÆ.

This family includes certain fossil forms of Lower Eocene age from the phosphatic deposits of Quercy in France, the {115}Wasatch strata of Wyoming, and the Puerco beds in New Mexico. Their dental formula is the same as that of existing Lemurs, namely I2/(2-1), C1/(1-0), P(2-3)/(2-3), M3/3. In some of the genera there is a tendency to develop, as Cope has pointed out, large cutting teeth in the position of incisors, "thus approaching the Aye-Aye." The posterior pre-molars are more simple than the anterior true molar, a character which indicates some relationship to the Mouse-Lemurs (Chirogale). The mastoidal or posterior portion of the ear-capsules, and the neighbouring squamosal region of the cranium are swollen, as among the Galagos.

GENUS MICROCHÆRUS.

Microchærus, Wood, Lond. Geol. Journ., i., p. 5 (1846).

Heterohyus, Gerv., Zool. et Pal. Fr., p. 202, pl. 35, fig. 14.

Necrolemur, Filhol, C. R., lxxxvii., p. 1112 (1873); id. Ann. Sc. Geol., viii., p. 55, pl. iv., figs. 213-217 (1877).

This genus is distinguished from all other Lemurs by "the angle of the mandible being produced into a large hook-like flange." (Flower and Lydekker.) The orbits are large, indicating a nocturnal animal; the inter-orbital space is wide, and distinguishes it from Loris. The dental formula is I2/1, C1/1, P3/3, M3/3. The canine teeth are not prominent; the anterior lower pre-molar is only slightly developed; a gap separates the anterior and the median upper pre-molars.

This genus is represented by five species. MICROCHÆRUS ANTIQUUS (Filhol) is of very small size, and has many affinities with Galago, as exhibited in the well-preserved cranium that has been recovered from the Phosphorites of Central France. The two lower molars have only one root. M. ERINACEUS, {116}Wood, from the Upper Eocene of Hampshire; M. EDWARDSI (Filhol), from Central France, a species larger than M. antiquus, presents dental characters similar to the Galagos and the Mouse-Lemurs; M. PARVULUS (Filhol), and M. ZITTELI (Schlosser), are both from the Quercy Phosphorites of France; while M. ARMATUS is from the Eocene of Alsace, and M. (CRYPTOPITHECUS) SIDEROLITHICUS from the Bonerg of Frohnstellen.

GENUS MIXODECTES.

Mixodectes, Cope, Proc. Amer. Phil. Soc., p. 447 (1883); id., Rep. U. S. Geol. Surv., iii., p. 240, pl. xxiv. f, figs. 1 and 2.

The members of this genus, founded on fragmentary mandibles from the Puerco (Lower Eocene) strata of New Mexico, have a large front tooth "issuing from the ramus at the symphysis like a rodent incisor, the second tooth being similar but smaller and posterior and external to the first." The genus is represented by two species, M. PUNGENS, Cope, and M. CRASSIUSCULUS, Cope.

GENUS CYNODONTOMYS.

Cynodontomys, Cope, Palæont. Bull., p. 151 (1882); id., Rep. U. S. Geol. Surv., iii., p. 243, pl. xxiv., fig. 2.

This genus contains but one species, founded on several lower jaws disinterred from the Wasatch beds in the Big-Horn Bad-lands, in Northern Wyoming. The lower incisors, or perhaps, canines, are very large and close to the line of union of the two halves of the jaw; the molars have three cusps in front and a heel behind. The dental characters of the genus "resemble considerably those of Anaptomorphus and Necrolemur [Microchærus] but the large size of the inferior canine {117}or incisor tooth distinguishes it from both." (Cope.) C. LATIDENS, Cope, is the only species.

GENUS OMOMYS.