THE LAST STEPS IN THE GENEALOGY OF MAN.*

By Dr. PAUL TOPINARD.
Translated by WALTER HOUGH.

Our science does not yet know the precise ways, direct or indirect, by which the present orders and families have advanced. The polyphyletic table of the genealogy of mammals that seems best to represent the present state of the inquiry, is far from having the ideal simplicity of the monophyletic tree of Hæckel. The genealogy of the celebrated professor of Jena is an admirable work, which has been the starting point for numerous studies that have rendered immense service. But he will himself acknowledge it to be a preliminary attempt, which he will certainly re-consider some day.

There are certain truths worthy to be remembered. The first is that our existing mammalian orders, families, and genera, are the product of a long evolution of successive transformations, and were not in existence before the eocene and miocene periods. At that time also according to the present teaching of paleontology, the first placental mammals began to be developed from the marsupials by means of differentiation and multiplication of types which have led to our present forms.

The second truth is that the progressive passage from the marsupial fauna of that time to the existing fauna did not take place by a single series of species for each order, family, or genus, but in all cases, where science has sufficient evidence, by multiple series anastomosing, intercrossing, and forming sometimes a perfectly inextricable network.

Here and there however, science seems already to have advanced;for instance, in the case of the ungulata, whose genealogical table has been tolerably made out; the carnivora, whose numerous origins have been shown; the cheiroptera, and the pinnipeds or aquatic carnivora. Other orders resemble a veritable cross-roads, as the insectivora and rodentia.

For some orders we have recorded only the probabilities or provis ional suppositions in regard to their derivation and development.

One important branch leading to man, in the doctrine of Hæckel, is that of the lemurs which follow the marsupials, the eighteenth stage from the moners in the genealogy of Hæckel.

* Lecture delivered in March, 1888, in the École d'Anthropologie of Paris. (From the Revue d'Anthropologie, May 15, 1888; 3 ser., vol. III, pp. 298-332.)

I.-LEMURS.

The lemurs have been classed among the quadrumana by Geoffroy Saint Hilaire, Cuvier, de Blainville, Duvernoy, and Milne Edwards, and among the primates by Linnæus, Lesson, Huxley, and Broca; that is to say, separated from man in the first case and re-united to him in the second. Vogt and Hæckel give them the name of pro-simians. The Germans call them half-apes (Halbaffen); the French sometimes the false-apes. The main question is, to what extent are they apes? Do they merit the name of pro-simians, and should they figure among the primates?

What do we understand by the primates? The best definition seems to be the following: The primates are non-aquatic, placental mammals (which excludes the cetacea, sirenia, and pinnipeds); they have no hoofs (which excludes the ungulata and proboscidea); they have three kinds of teeth (which sets aside the rodentia and edentata), and their molars are not in sharp and cutting ridges, or with sharp and conical points (which excludes the carnivora and insectivora).

But have they not certain characters in common? Not absolutely. Naturalists omit in their scheme of characters the type of cerebral convolutions. The primates have a discoidal placenta, a uterus with a cavity not two-horned, and the penis pendant.

Passing over the first two characters, the third is observed likewise in the cheiroptera or bats. The primates have two pectoral mamma, but so have the cheiroptera and sirenia.

The teeth that every where furnish characters of the first order, vary as to number, form, and degree of continuity: all we are able to say here is that they are much more specialized, much closer together, and are above all, much more fixed in their general formula, as the families rise toward man.

Under the last head there are four stages: the lemurs, the monkeys of the old world, the monkeys of the new world, and man.

The nails, which among the primates take the place of claws, are one of their most important characteristics. So long as the claws are horny productions, compressed transversely, more or less long, recurved and sharp pointed, they serve as organs of attack and defense; and in the hoof the horny growth curves in on every side and envelops the digi tal extremity to hinder direct contact with the ground, and adapt it exclusively to walking. The nails are horny growths flattened above and below, growing straight and serving to facilitate prehension and touch. Their adaptation to that use is more or less perfect and applies more or less to the fingers of the primates; this allows us again to divide them into perfect primates, such as man and the monkeys (minus a certain group), and the imperfect primates.

The well developed thumb, separated from the other fingers and opposable, is a character of adaptation, the corollary of the nails. More completely, it is besides an organ for clamping, for seizing, and for

touching; by this the primates may be sub-divided also, but into three groups, viz: Man, in which the thumb is opposable only in the upper extremities; the monkeys, in which it is opposable in all of the extremities, and the imperfect primates in which the adaptation may be either less apparent, or more marked, in the lower extremities than in the upper. Other characters could be pointed out, for the most part showing grades in the ascending series of the primates; but the above are sufficient for our purpose.

To so consider the primates is perhaps to prejudice in a measure the result sought. As soon as one introduces into the series a progressive development of characters, and divides the primates into superior, medium, and inferior, one is held to be indulgent toward the characters which appear to be obscure or lacking among the lowest. When we admit that the lower primates are but the commencement of the series, the passage from the other orders to that of the primates is but a step. Now the lemurs will supply us with the greater part of the imperfect primates to which we have alluded.

The lemurs embrace, or should embrace, three groups of animals: the galeopitheci, the cheiromys, and the lemus properly so called.

The galeopitheci, or flying cats (from raiǹ cat and 107203, monkey) inhabit the Sunda, Molucca, and Philippine islands. They exemplify the difficulty of fixing in our classification certain groups characterized as paradoxical, and for the reason that they are groups of transition, having the right really to be found in many groups. By Oken they have been classed with the rodents, by Étienne Geoffroy Saint Hilaire with the carnivora, by Cuvier with the bats, by Linnæus, Broca, Brehm, Huxley (in 1862), and Vogt, with the lemurs, and by Huxley (in 1872), with the insectivora.

That which permits of their being called lemurs is their general appearance and their arboreal and nocturnal habits. Most of their characters however oppose it. They have claws on all the fingers, and the thumb is not opposable, hence they are not primates, not even incipient. They possess that which Mr. Huxley calls a patagium, that is, a fold of skin on the sides of the body extending along the outside of the lower limbs and along the outside of the upper limbs, encircling the tail and prolonged between the fingers of normal length. It is the organ exhibited among the flying marsupials called petaurites, and which modified recalls the jurassic pterosaurians on the one hand, the cheiroptera and particularly the pteropus on the other, without agreeing among the last, however, with the wing of a bird.

This patagium has caused the galeopitheci to be classed with the cheiroptera. That which causes them to be placed among the insectivora by Professor Huxley is their dentition, the conformation of their skull, and their brain. In short, we discard them from the lemurs and consequently from the primates.

The cheiromys embraces but one genus, the aye-aye of Madagascar.

It resembles a squirrel, but it also approaches the monkeys and maki. It has claws only on the upper limbs; the thumb is freely developed and is not opposable. In the lower limbs four of the fingers have claws; the well-developed thumb has a flat nail and is opposable. Its dentition is curious, making it a rodent as an adult, and an insectivore or lemur when an infant at its first dentition. Owen, de Blainville, Huxley, Brehm, and Vogt all place them among the lemurs. It is evidently a primate at its inception; but a species as if hesitating whether it should remain in the primates or in the rodents. The exposition of M. Vogt, on pages 13 and 77 of his "Mammalia," implies that its origin was in the insectivora.

The lemurs proper are divided into fossil and recent. The former appeared in the Eocene, and at that time existed parallel with the mar supials, which were then in the course of extinction, and the first placental mammals, which were the carnivores, the rodents, the ungulates and the insectivores. Europe has furnished five genera, America more, the most important being the auaptomorphus, from which Professor Cope derives man. The present species may be divided into three geographical groups. The first and the most numerous embraces the island of Madagascar, the second that island and Africa south of the Sahara. The third the island of Ceylon, the peninsula of Malacca, the Moluccas, and the Philippines. These regions constitute in the theory of Haeckel the remains of a vast austral continent, which he has called Lemuria. Among the genera belonging to the group of Madagascar I cite the maki, the indris, and the tarsius; in the second group, the galago, of which a species is found only however in Madagascar; and in the third or oriental group the loris.

The lemurs are arboreal and nocturnal animals, as previously said. Oken calls them the nocturnal monkeys of the Old World. They have four opposable thumbs with a single exception, the tarsier, which does not have the upper thumbs opposable, but only the lower ones. All their fingers, as a general rule, have nails, save the posterior index, which is armed with a claw, or the anterior little finger of the loris. However, the nails are sometimes rudimentary and as though developing from the claw. Relative to the teeth it is impossible to establish a general formula. The number varies from thirty to thirty-six. For example, the formula of thirty-two has been given to man and the catarrhine apes; the indri has thirty, because it lacks an upper premolar; the tarsier thirty-four, because it has a lower incisor less and for each jaw a premolar more; the maki thirty-six, because it has a lower incisor and an upper premolar extra; the Loris also thirty-six, because it has an incisor and a lower premolar more. All these considerations tend to establish that the lemurs have not a fixed and homogeneous type, but that they constitute a transitional group from animals with claws to animals with nails, and should consequently be regarded as the first, if not the second, step (considering cheiromys as

the first) in the line of the better-characterized monkeys. However, serious objections are raised against that way of looking at it. The first is that of Broca. In 1870, when his celebrated monograph on the order of primates appeared, my lamented master (Broca) maintained in nearly the same terms as Huxley that the lemurs are the fifth family of the order of primates, but more separated from the other families than any one of those is from one another.

In 1877, after a communication before the Société d'Anthropologie, he changed his opinion, and for the following reason: Haeckel based his bifurcate division of placental mammals on the existence of extended or limited placenta and the absence or presence of a deciduous membrane which detaches with the débris of the egg at the time of birth. Among the mammals with diffuse and deciduous placenta are classed the ungulata and cetacea. The others are sub-divided in their turn into four branches, in which the circumscribed placenta presents itself under different aspects reducible to two, one an annular or zone-like insertion, the other a disk or discoidal insertion. The carnivora and proboscidea are examples of the first mode of insertion. Man, the anthropoids, the ordinary monkeys, and the lemurs,-that is to say, all the primates are in the second class. Now Broca had shown to the society the placenta of a lemur, the propithecus diadema, in which the placenta was neither discoidal nor annular, but is diffuse, and which had no decidua. The lemurs hence are separated violently from the other primates by a character of the first order.

Vogt answered that we have as yet examined but four specimens of lemurian placentas, and that this organ among them is neither diffuse nor zonary, nor discoidal, but bell-shaped, a transition from the zonary to the discoidal. Afterwards, without denying the importance of the placenta as a basis of classification for the mammals, he showed that its importance had been exaggerated, that all the intermediate ones fall in between the different forms, and that very different shapes may fre quently be observed in the same order. Vogt accepts however the opinion of Broca, but it was on account of other considerations. According to him the lemurs are to be separated from the monkeys, and consequently are not their ancestors. He remarked that the opposable thumb has nothing absolute about it since it has been already observed among certain marsupials, and likewise the nails, since the lemurs have claws on more or fewer fingers. That is true, but Vogt retains the galeopitheci among the lemurs, and they are the most important feature in his argument. As to the contradictory physical characters invoked by Vogt they are numerous and weighty. To enumerate: -the lemurs have the two parts of the jaw independent, but they are always joined among the primates; their low and slim jaw contrasts with the high and heavy jaw of the monkeys. The intermaxillary bone persists throughout life among the lemurs but it is co ossified early among the recognized primates. The orbits are opened behind or have but a H. Mis, 224-43