448 



NATURE 



{Sept. 20, 1877 



country, and especially rich in the finest timber and many other 

 vegetable products — none utilised. The only article which 

 finds its way abroad is caoutchouc, and enormous quantities of 

 this have been exported duiing the last ten years, but the export 

 begins gradually to decrease, since the workmen, instead of only 

 tapping the trees, destroy them completely. The province is 

 inhabited by a population of only 10,000 natives, who live along 

 the coast. The whole of the interior is covered by one gigantic 

 virgin forest, and accessible only in canoes upon the rivers. Of 

 the three months of my journey I spent more than two in canoes, 

 which are rather small and hardly comfortable, or adapted for a 

 travelling naturalist ; the last twenty-three days I spent unin- 

 terruptedly in a canoe on the Esmeraldas River and its tribu- 

 taries. The rivers are very rapid and not without dangers ; 

 but then my journey was made during the middle of the 

 rainy season, when the rivers are very much swollen. On the 

 Cayapas River I made the acquaintance of the wild Cayapas 

 Indians, a very interesting tribe with a language and customs of 

 then- own. They keep in perfect isolation from other tribes, 

 living in forests, hunting and fishing, going almost naked, and 

 painting their bodies ; on the whole they are very harmless, and 

 may be some 2,000 in number." 



In the Nachrichten %'on der Cesellschuft der IVissenschafkn zu 

 Golliiii;eii, Herr Edmund Hoppe gives an account of some 

 experiments he made with a view to determine the resiscance 

 offered by flames to the galvanic current. He arrived at the 

 following results : (i) In each flame the greater galvanic con- 

 ducting power depends on the greater heat and the greater 

 quantity of burning gas. (2) With different .flames the con- 

 ducting power depends on the burning substances ; the salts o' 

 potassium, sodium, barium, strontium, lithium, thallium, and 

 copper in particular increase greatly the conducting power of 

 the hydrogen flame. (3) Ohm's law applies perfectly to flames. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey {Macacus cynomolgus) 

 from India, presented by Mr. A. S. Percival ; an Osprey {Pandion 

 haliacliis) from Yorkshire, presented by Mr. W. H. S. Quintin ; a 

 Common Hangnest (Icterus vulgaris) from South America, pre- 

 sented by Mr. Hamilton Dunlop ; a West African Python 

 {Python Slice) from West Africa, presented by Mr. Francis 

 Lovell ; two Guilding's hm^acions {Chrysotis guiUlingi) liom St. 

 Vincent, a Violet Tanager {Eiip/witia violaced), a Yellow-winged 

 Blue Creeper (Cmrd'a cyaiiea), a Common Boa (Boa constrictor) 

 from South America, deposited ; three Capybaras (Hydrocharns 

 capybara) from South America, purchased. 



INTRODUCTION AND SUCCESSION OF 

 VERTEBRATE LIFE IN AMERICA • 

 'T'HE origin of life, and the order of succession in which its 

 -'■ various forms have appeared upon the earth, off'er to science 

 its most inviting and most difficult field of research. Although 

 the primal origin of life is unknown, and may perhaps never be 

 known, yet no one has a right to say how much of the mystery 

 now surrounding it science cannot remove. It is certainly within 

 the domain of science to determine when the earth was first fitted 

 to receive life, and in what form the earliest life began. To trace 

 that life in its manifold changes through past ages to the present 

 is a more difficult task, but one from which modern science does 

 not shrink. In this wide field every earnest elTort will meet 

 some degree of success ; every year will add new and important 

 facts ; and every generation will bring to light some law, in 

 accordance with which ancient life has been changed into life as 

 we see it around us to-day. That such a development has t.aken 

 place no one will doubt who has carefully traced any single group 

 of animals through its past history, as recorded in the crust of 

 the earth. The evidence will be especially conclusive if the 

 group selected belongs to the higher forms of life, which are 



' Lecture delivered at the Nashville meeting of the American Association, 

 August 30, 



sensitive to every change in their surroundings. But I am sure 

 I need offer here no argument for evolution ; since to doubt 

 evolution to-day is to doubt science, and science is only another 

 name for truth. 



Taking, then, evolution as a key to the mysteries of past life 

 on the earth, I invite your attention to the subject I have 

 chosen: The Introduction and Succession of Vertebrate Life 

 in America. 



In the brief hour allotted to me I could hardly hope to give 

 more than a very incomplete sketch of what is now known on 

 this subject. I shall therefore pass rapidly over the lower 

 groups, and speak more particularly of the higher vertebrates, 

 which have an especial interest to us all, in so far as they ap- 

 proach man in structure, and thus indicate his probable origin. 

 The^e higher vertebrates, moreover, are most important witnesses 

 of the p.ast, since their superior organisation made them ready 

 victims to slight climatic changes, which would otherwise have 

 remained unrecorded. 



In considering the ancient life of America it is important to 

 bear in mind that I can only offer you a brief record of a few 

 of the countless forms that once occupied this continent. The 

 review I can bring before you will not be like that of a great 

 army, when regiment after regiment with full ranks moves by 

 in orderly succession, until the entire ho5t has passed. My 

 review must be more like the roll-call after a battle, when only 

 a few scarred and crippled veterans remain to answer to their 

 names. Or rather, it must resemble an array of relics, dug 

 from the field of some old Trojan combat, long after the contest, 

 when no survivor remains to tell the tale of the strife. From 

 such an ancient battle-field a Schliemanii might unearth together 

 the bronze shield, lance-head, and gilded helmet of a prehistoric 

 leader, and learn from them with certainty his race and rank. 

 Perliaps the skull might still retain the b.arbaric stone weapon 

 by which his northern foe had slain him. Near by the explorer 

 might bring to light the commingled coat of mail and trappings 

 of a horse and rider, so strangely different from the equipment 

 of the chief, as to suggest a foreign ally. From these, and 

 from the more common implements of war that fill the soil, the 

 antiquary could determine, by patient study, what nations 

 fought, and perhaps when and why. 



By this same method of research the more ancient strata of 

 the earth have been explored, and in our western wilds, veritable 

 battle-fields, strewn with the fossil skeletons of the slain, and 

 guarded faithfully by savage superstition, have been despoiled, 

 yielding to science treasures more r.ire than bronze or gold. 

 Without such spoils, from many fields, I could not have chosen 

 the present theme for my address to-night. 



According to present knowledge, no vertebrate life is known 

 to have existed on this continent in the Archrean, Cambrian, or 

 Silurian periods ■ yet during this time more than half of the 

 thickness of American stratified rocks was deposited. It by no 

 means follows that vertebrate animals of some kind did not exist 

 here in those remote ages. Fishes are known from the upper 

 Silurian of Europe, and there is every probability that they will 

 yet be discovered in our strata of the same age, if not at a still 

 lower horizon. 



In the shore deposits of the early Devonian sea, known as the 

 Schoharie grit, characteristic remains of fishes were preserved, 

 and in the deeper sea that followed, in which the corniferous 

 limestone was laid down, this ckass was well represented. 

 During the remainder of the Devonian fishes continue abundant 

 in the shallower seas, and, so far as now known, were the only 

 type of vertebrate life. These fishes were mainly ganoids, a 

 group represented in our present waters by the gar-pike {Lcpi- 

 dostcus) and sturgeon (Acipenser), but, in the Devonian sea, 

 chiefiy by the placoderms, the exact aflinifies of which are soifie- 

 what in doubt. With these were elasmobranchs, or the shark 

 tribe, and among them a few chim.\.'roids, a peculiar type, of 

 which one or two members still survive. The placoderms were 

 the monarchs of the ocean. All were well protected by a 

 massive coat of armour, and some of them attained huge dimen- 

 sions. 1"he American Devonian fishes now known are not as 

 numerous .as those of Europe, but they were larger in size, and 

 mostly inhabitants of the open sea. Some twenty genera and 

 forty species have been described. 



The more important genera of placoderms are Dinichthys, 

 Aspidichthys, and Diplognathus, our largest palaeozoic fishes. 

 Others are, Acant/iaspts, AcanthoUpis, Coccostens, jMacropeta- 

 lichthys, and Oiiyc/iodus. Among the elasmobranchs were, 

 Cladodiis, CtenacanthuSf Alac/iuracanthus^ RhynchodtiSf and 

 Ptyctodiis, the last two being regarded as chimeroids. In the 



