472 



NATURE 



{Sept. 27, 1877 



I can offer you no better illustration than this of the advance 

 vertebrate paleontology has mide during the last decade, or of 

 the important contributions to this progress which our Rocky 

 Mountain region has supplied. 



The oldest representative of the horse at present known is the 

 diminutive £o/npf<iis from the lower eocene. Several species 

 have been foun'1, all about the size of a fox. Like most of 

 the early mammals, these ungulates had fourty-four teeth, the 

 molars with short crowns, and quire distinct in form from the 

 premolars. The ulna and the fibula were entire and distinct, 

 and there were four well-developed toes and a rudiment of 

 another on the fore-feet, and three toes behind. In the structure 

 of the feet and in the teeth, the F.ohippus indicates unmistakably 

 that the direct ancestral Xm.-. to the modern horse has already 

 ."^epara^ed from the other perissodactyles. In the next higher 

 division of the eocene another genus (O^'ohippus) makes its ap- 

 pearance, replacing iLohippus, and showing a greater, although 

 still distant, resemblance to the equine type. Tlie rudimentary 

 fir^t digit of the fore-foot has disappeared, and the last premolar 

 has gone over to the molar series. Orohtppus was but little 

 larger than Kohippus^ and in most other respects very similar. 

 Several species have been found in the same horizon vi\\.\v Ditto- 

 ceras, and others lived during the upper eocene with Diplacodon, 

 but none later. 



Near the base of the tniocene, in the brontotherium beds, we 

 find a third closely-allied genus, Mcso/iippiis, which is about as 

 large as a sheep, and one stage nearer the horse. There are 

 only three toss and a ru limntary splint bone on the fore-feet, 

 and three toes behind. Two of the preoioUr teeth are quite like 

 the molars. The ulna is no longer distinC, or the fibula eniire, 

 and other characters show clearly that the transition is adv.-incing. 

 In the upper miocene Misohippus is not found, bat in its place a 

 fourth form, Mio/iippus, continues the line. This genus is near 

 the Anchitherium of Europe, but presents several iniprirtant 

 differences. The three toes in each foot are more nearly of a 

 size, and a rudiment of the lifih metacarpal bone is retained, 

 All the known species of this genus are larger than those of 

 Mesohippus, and none pass above the miocene. 



The genus, Protoliippus of the lower pliocene, is yet more 

 equine, and some of its species equalled the ass in size. There 

 are still three toes on each foot, but only the middle one, cor- 

 responding to the single toe of tlie horse, comes to the ground. 

 This genus resembles most nearly the Hipparion of Europe. In 

 the pliocene we have the last stage of the series before reaching 

 the liorse, in the genus PHohippus, which has lost the small 

 hooflets, and in other respects is very equine. Only in the upper 

 pliocene does the true Eijiius appear and complete the genealogy 

 of the horse, which in the post-tertiary roamed over the whole of 

 North and South America and soon after became extinct. This 

 occurred long before the discovery of the Continent by Euro- 

 peans, and no satisfactory reason foi the extinction has yet been 

 given. Besides the characters I have mentioned there are many 

 others in the skeleton, skull, teeth, and brain of the forty or 

 more intermediate species, which show that the transition from 

 the eocene Eohippiis to the modern Eijiius has taken place in 

 the order indicated, and I believe the specimens now at New- 

 Haven will demonstrate the fact to any anatomist. They 

 certainly carried prompt conviction to the first of anatomists who 

 was the honoured guest of the Association a year ago, whose 

 genius had already indicated the later genealogy of the horse in 

 Europe, and whose own researches so well qualified him to 

 appreciate the evidence here laid before him. Did time permit 

 I might give you at least a probable explanation of this mar- 

 vellous change, but justice to the comrades of the hor-se in his 

 long struggle for existence demands that some notice of their 

 efforts should be placed on record. 



( To be continued. ) 



SOCIETIES AND ACADEMIES 



Paris 

 Academy of Sciences, September 17. — M. Peligot in the 

 chair. — The president requested the meeting to designate one of 

 their fellows to represent the Academy in the annual public 

 meeting of the five academies, which will take place on October 

 25. — M. Tresca then, in the name of M. Leverrier, presented to 

 the Academy vol. viii. of the " Atlas Meteorologique de I'Obser- 

 vatoire de Paris pour Fan 1876." — A note by M. Faye, on the 

 atlas of the superior movements of the atmosphere, by M. H. 



Hildebrandsson. The author bases his work on the observation 

 of cirrhus clouds. — A note by M. G. de Saporta on the discovery 

 of fossil plants in the tertiary strata in the vicinity of the North 

 Pole. — On an erratic block of granite situated in the neighbour- 

 hood of Geneva, by M. de Marignac. It appears that the block 

 in question is a mass of about 300 cubic metres of granite, and 

 that the prefect of the Department, Haute Savoie, has given 

 permission to a Railway Company to take possession of it and 

 to cut it to pieces. M. de Marignac, who is the owner of the 

 ground upon which it lies, now recommends the preservation of 

 the block and offers it to the Acadeny together with the area it 

 lies up'in, unier the sole condition that it sh'.ll be preserved. 

 M. Dumas spake in favour of M. de Marignac's proposition. — 

 On the spont\neous disappearance of phylloxera, by H. Mare;. 

 — M. P. de Tchihatcheff then presented to the Academy his 

 translati m of M. Grisebich's work, "The Vegetation of the 

 Globe," and made some remarks on the same. — M. Alluard 

 read a memoir on a new condensation-hys;rometer, invented by 

 himself. — A letter from M. E. Stephan announcing the discovery 

 of a new comet by M. Cog^ia was read. (Of this we gave 

 the details in the Astronomical Column of our last number, 

 p. 442.) The letter further contained details of an observalion of 

 one of the satellites of Mars, by M. Borrelly, made at Mar- 

 seilles. — M. Leverrier transmitted to the Academy details of 

 MM. Paul and Prosper Henry's observation of the same 

 satellite, made with the equatorial in the garden of the Paris 

 Observatory. — M. P.,H. Boutigny pointed out that in a pas- 

 sage in his work, "ICtudes sur les corps a Te^at spheroidal," 

 published some thirty years ago, he expressed his belief in the 

 existence of s-atellites of Mars and pronounced the hope of their 

 future discovery. — New researches on the ammoniacal fermenta- 

 tion of urine and spont.ineous generation, by MM. P. Cazeneuve 

 and Ch. Livon. — Oa the physiological action of salicylate of 

 soda, by MM. Bochefontaine and Chabbert. — .\ note by M. V. 

 Duram on a luminous meteor observed on September 11 atBaen 

 (Loire), and on a shock of earthquake felt at the same place on 

 September 12. The meteor was of unusual brilliancy ; it 

 appeared in the east of the sky at 7.45 P.M. ; its elevation above 

 the horizon was but small ; it left a long curved trail, and its 

 appearance was marked by a slight detonation ; the direction of 

 its path was from north to south. The shock of earthquake was 

 felt at 6h. 52in. true time, and lasted several seconds. — M. Faye 

 then drew the attention of the Academy to a memoir just pub- 

 lished by M. P. de Saint Robert, on the spherical mavement of 

 the pendulum, with regard to the resistance of the air and the 

 rotation of the earth. 



CONTENTS pacb 



Urban J. J. Leverrier 453 



Recent Botanical Books 453 



Our Book Shelf : — 



Maull's "Natural Geometry: an Introduction to the Logical 

 . Study of Mathematics, for the Use of Schools and Technical 



Classes, with Explanatory Models " .,5; 



Letters to the Editor : — 



Tne Cycle of Sun-spots and Rainfall.— Dr. W. W. Hunter . . 45, 



The Discovery of the Satellites of Mars.— Prof Simon Newcomb . 437 

 TheSatellitesof Mars.— The Earl of ROSSE.FR.S. ; Rev. Henry 



Cooper Key 456 



A Good Suggestion —Dr. J. W. Mallet 457 



Some of the Troubles of John O'Toole respecting Potential 



Energy, IL— X 457 



New Electric Lights.— W. Mattieu Williams 459 



Serpula Parallela —Dr. John Young 4G0 



HvunocRAPiiic Survey of the Baltic 460 



Our Astronomical Column :— 



The Saturnian Satellite Hyperion , ^^q 



The New Comn (7877, IV.)J 460 



Famines and Shipwrecks. By Prof. Balfour Stewart, F.R.S. . 461 



Prof. Adams on Leverrier's Planetary Theories 462 



Notes 464 



The Direct Process in the Production of Iron and Steel. By 



Dr. C. William Siemens, F.R.S 467 



The Ameuican Association at Nashville 469 



Introduction AND Succession of Vertebrate Life in A.merica, 



II. By Prof O. C. Marsh 470 



Societies and Academies 472 



