Dec. 4, 1879] 



NATURE 



103 



from the lower Pliocene, there is a considerable increase 

 in size, the splint has disappeared, and the two side toes 

 have become so small that they no longer reach the 

 ground, but are merely dew claws, like those of the deer 

 or ox. Pliohippus, which is found in a still higher horizon 

 of the Pliocene, is as large as a donkey, has lost the dew 

 claws, but has the splints much longer than the same 

 bones in the modern equines. Finally, at the top of the 

 Pliocene comes a true Eguus, which completes the line- 

 Besides the forms mentioned, there are many intermediate 

 ones, which show that the transition has taken place in 

 the order indicated. Many additional characters of the 

 skull, brain, and teeth, add weight to, and confirm, the 

 evidence furnished by the feet. 



Among the other treasures of the Museum are bones of 

 mammals allied to the modern rhinoceros, which occur 

 abundantly in strata, said to be of Miocene age, both in 

 Oregon and the Rocky Mountain region. These remains 

 furnish material for tracing the descent of these creatures 

 from the upper Eocene to the close of the Pliocene, when 

 they appear to have become extinct. A strange group of 

 ungulates, found in the so-called Lower Miocene of the 

 plains, were the huge Brontotherida, which appear to 

 have been allied to the Dinoccrata, and also to Rhinoceros. 

 In size they equalled the Dinoccrata, and, like them, had 

 an elevated pair of horn cores on the maxillary bones. 

 An immense quantity of the remains of these animals, 

 representing several genera and over two hundred indi- 

 viduals, has been collected, and is now in the Museum. 



Until within a year or two, no Tertiary edentates were 

 known from America, although their remains were found 

 in abundance in the superficial post-Tertiary deposits. 

 Recently, however, the Museum has received, from the 

 " Lower Miocene " of Oregon, the remains of two species 

 belonging to this group and to the genus Moropus. These 

 are of large size, and were, essentially, huge sloths. From 

 the Pliocene deposits of Idaho and California, and from 

 the same formations east of the Rocky Mountains, other 

 large species have been discovered belonging to the 

 genera Moropus and Morotherium. Many other groups 

 of mammals, including primates, carnivores, suillines, 

 camels, &c, have been collected in these formations 

 which also yield numerous birds, reptiles, and fishes. 



Although observations had been made by previous 

 investigators, on the size of the bram in Tertiary mammals, 

 Prof. Marsh was the first to institute any systematic 

 inquiry into the laws which governed and the causes 

 which acted upon, brain-growth in these ancient animals. 

 Some of his conclusions, based on specimens now in the 

 Museum, have been already given to the world, but they 

 maybe fittingly cited here: (1) All Tertiary Mammals 

 had small brains ; (2) there was a gradual increase in 

 the size of the brain during Tertiary time ; (3) this in- 

 crease was mainly confined to the cerebral hemispheres, 

 or higher portion of the brain ; (4) in some groups the 

 convolutions of the brain have gradually become more 

 complicated; (5) in some the cerebellum and olfactory 

 lobes have even diminished in size. 



Some of the additional conclusions already reached in 

 regard to American Tertiary mammals, so far as they are 

 now known, are stated as follows : — (1) All the Ungulate 

 from Eocene and Miocene deposits had upper and lower 

 incisors ; (2) all Eocene and Miocene mammals had 



separate scaphoid and lunar bones ; (3) all mammals 

 from these formations had separate metapodial bones. 



Although the Cretaceous and Tertiary fossils make up 

 a large part of the geological collections of the Peabody 

 Museum, the other formations are well represented in its 

 store-rooms. This is especially true of the recently dis- 

 covered Jurassic beds of the Rocky Mountains, which 

 have yielded, since the summer of 1 877, a great number 

 of interesting forms. The parties that have been collect- 

 ing for Prof. Marsh have been more than usually success- 

 ful, and a study of the strange animals, many of them 

 new to science, which have been sent to the Museum, has 

 resulted in several discoveries of great interest. These 

 Jurassic fossils are chiefly dinosaurs, crocodiles, turtles, 

 and fishes. The first of these are extremely abundant, 

 and the horizon from which they come has been named 

 by Prof. Marsh, from one of the genera there discovered, 

 the Atlantosaurus Beds. These dinosaurs varied widely 

 in size and structure, for while some of them, e.g., Nano- 

 saurus, were no larger than a cat, others were, by fan 

 the largest land animals of which we have any knowledge. 

 Among the discovered remains of Atlantosaurus immanis 

 is a femur over six feet in length. A comparison of this 

 specimen with the same bone in living reptiles indicates 

 that Atlantosaurus, if similar in proportions to the croco- 

 diles, would have been more than one hundred feet in 

 length. The anatomical points cleared up by the dis- 

 covery of the bones of the feet in these dinosaurs are of 

 great importance and interest. From these same Atlanto- 

 saurus Beds come the strange Stegosauria, recently de- 

 scribed by Prof. Marsh ; a new] order of reptiles whose 

 affinities are, as yet, but imperfectly understood, but 

 which appear to have most relationship with the dino- 

 saurs. The Atlantosaurus Beds have .furnished, more- 

 over, the only Jurassic mammals yet found in America. 

 These remains, apparently all marsupial, belong, so far 

 as known, to four genera and eight species, which Prof. 

 Marsh has described. He has also recently made known, 

 from the marine Jurassic beds of the Rocky Mountains, 

 a peculiar group of reptiles (Sauranodonlida) allied to 

 Ichthyosaurus, but without teeth. 



An enumeration of the fossil treasures of New Haven 

 would, however, fail to do justice to this marvellous col- 

 lection if it made no mention of the almost incredible 

 state of preservation of the fossils. A European student 

 is lucky if he finds a tooth or a jaw ; most fortunate 

 should he stumble upon a cranium ; the envy of the 

 whole tribe of collectors should he disinter a whole 

 skeleton. But even when most successful he meets with 

 the bones often in a fragmentary, or badly preserved 

 condition, or imbedded in so tough a matrix that they 

 cannot be adequately cleared for study without almost 

 certain detriment. The vast regions open to American 

 research in the West, however, are the very paradise of 

 palaeontologists. Almost as fresh as if the animals had 

 only recently died, the bones protrude sometimes in great 

 numbers from the edges of the escarpments. When the 

 first explorers went into these tracts they found the skulls 

 grinning at them from the faces of the bare dry verdure- 

 less cliffs of the "bad lands." The diligence of Pro- 

 fessors Marsh, Cope, and their parties has no doubt 

 cleared away a good many of the prominent objects. 

 But the number still to be exhumed must be enormous- 



