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PAGE Leaf Butterfly in flight and repose (from Mr. A. Wallace’s “Malay's Archispelago”) . to e to & e * e so g 43 Walking-Leaf Insect © o © to & & e * 47 Pleuronectidae, with the peculiarly placed eye in different positions (from Dr. Traguair's paper in Linn. Soc. Trans., 1865) . e so to 49, 180 Mouth of Whale (from Prof. Owen’s “Odontography”) g o to 53 Four plates of Baleen seen obliquely from within (from Prof. Owen's “Odon

tography”) g * * * * & § e & 54 Dugong e o g e Q o * * e e 54, 189 Echinus or Sea Urchin o e * e te e to . 56, 181 Pedicellariae of Echinus very much enlarged . * > e e to 59 Rattlesnake . g e te & so o g e e 62 Cobra (from Sir Andrew Smith’s “Southern Africa”) . o Q 63

Wingbones of Pterodactyl, Bat, and Bird (from Mr. Andrew Murray's
“Geographical Distribution of Mammals”) . e * . 77, 144, 171
Skeleton of Flying-Dragon . e so e * * . 78, 172
Centipede (from a specimen in the Museum of the Royal College of Sur-
geons) e e * & o * $ * e . 79, 173
Teeth of Urotrichus and Perameles • & wo © 9. 82
The Archeopteryx (from Prof. Owen’s “Anatomy of Vertebrata") . . 86, 146
Cuttle-Fish . g g © § & e go so e 88, 155
Skeleton of Ichthyosaurus . e e * e e 92, 121, 146, 191
Cytheridea Torosa (from Messrs. Brady and Robertson's paper in Ann, and
Mag. of Wat. Hist., 1870) e g ge e e © ge 93
A Polyzoon, with Bird's-head processes . e e g § so 94
Bird's-head processes greatly enlarged © & e e © to 95
Antechinus Minutissimus and Mus Delicatulus (from Mr. Andrew Murray's
“Geographical Distribution of Mammals”) to & Q o 96
Outlines of Wings of Butterflies of Celebes compared with those of allied spe-
cies elsewhere & * g g e c g o e
Great Shielded Grasshopper e & & • e o o
The Six-shafted Bird of Paradise . & e e & g o
The Long-tailed Bird of Paradise e * & g & {-
The Red Bird of Paradise . © e e {o e to •
Horned Flies so & go to e 7 & . to © so
The Magnificent Bird of Paradise . e § & e *
(The above Seven figures are from Mr. A. Wallace’s “Malay Archo-

Much enlarged horizontal Section of the Tooth of a Labyrinthodon (from Prof.
Owen’s “Odontography”) e e {e & e o e
Hand of the Potto (from life) . go e * e to *
Skeleton of Plesiosaurus ge to to o ‘o so . 120,

The Aye-Aye (from Trans, of Zool. Soc.) . . * & e
Dentition of Sabre-toothed Tiger (from Prof. Owen's “Odontography”) .
Trilobite . so & o g * to e e ©
Inner side of Lower Jaw of Pleurodont Lizard (from Prof. Owen's “odontog-

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Solenodon (from Berlin Trans.) . {o e o * ge
Tarsal Bones of Galago and Cheirogaleus (from Proc. Zool. Soc.) . *
Squilla . e e . . . . • . . .
Parts of the Skeleton of the Lobster . . . e o ©
Spine of Galago Allenii (from Proc. Zool. Soc.) . e e to. o
Vertebrae of Axolotl (from Proc. Zool. Soc.) . * © e c
Annelid undergoing spontaneous fission . e © e

Aard-Wark (Orycteropus capensis) . g & * & e
Pangolin (Manis) wo so to e e * * so e
Skeleton of Manus and Pes of a Tailed Batrachian ( jrom Prof. Gegenbaur's
“Tarsus and Carpus”) . to © o e to o
Flexor Muscles of Hand of Nycticetus (from Proc. Zool. Soc.) . e ge
The Fibres of Corti e to e © o e © e


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118 119 147, 192 122 125 149, 185

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The Problem of the Genesis of Species stated.—Nature of its Probable Solution.—Importance of the Question.—Position here defended.—Statement of the DARWINIAN THEORY..—Its Applicability to Details of Geographical Distribution; to Rudimentary Structures; to Homology; to Mimicry, etc.—Consequent Utility of the Theory.-Its Wide Acceptance.—Reasons for this, other than, and in Addition to, its Scientific Value.—Its Simplicity.—Its Bearing on Religious Questions.—Odžum. Theologicum? and Odium, Antitheologicum.—The Antagonism supposed by many to exist between it and Theology neither necessary nor universal.—Christian Authorities in favor of Evolution.—Mr. Darwin's “Animals and Plants under Domestication.”— Difficulties of the Darwinian Theory enumerated.

THE great problem which has so long exercised the minds of naturalists, namely, that concerning the origin of different kinds of animals and plants, seems at last to be fairly on the road to receive—perhaps at no very distant future—as satisfactory a solution as it can well have.

But the problem presents peculiar difficulties. The birth of a “species” has often been compared with that of an “individual.” The origin, however, of even an individual animal or plant (that which determines an embryo to evolve itself—as, e.g., a spider rather than a beetle, a roseplant rather than a pear) is shrouded in obscurity. A fortiori must this be the case with the origin of a “species.”

Moreover, the analogy between a “species” and an “individual” is a very incomplete one. The word “individual” denotes a concrete whole with a real, separate, and distinct existence. The word “species,” on the other hand, denotes a peculiar congeries of characters, innate powers and qualities, and a certain mature realized indeed in individuals, but having no separate existence, except ideally as a thought in some mind. Thus the birth of a “species” can only be compared metaphorically, and very imperfectly, with that of an “individual.” Individuals, as individuals, actually and directly produce and bring forth other individuals; but no “congeries of characters,” no “common nature” as such, can directly bring forth another “common nature,” because, per se, it has no existence (other than ideal) apart from the individuals in which it is manifested. The problem then is, “By what combination of natural laws does a new ‘common nature’ appear upon the scene of realized existence P’ i.e., how is an individual embodying such new characters produced ? For the approximation we have of late made toward the solution of this problem, we are mainly indebted to the invaluable labors and active brains of Charles Darwin and Alfred Wallace. Nevertheless, important as have been the impulse and direction given by those writers to both our observations and speculations, the solution will not (if the views here advocated are correct) ultimately present that aspect and character with which it has issued from the hands of those writers. Neither, most certainly, will that solution agree in appearance or substance with the more or less crude conceptions which have been put forth by most of the opponents of Messrs. Darwin and Wallace. Rather, judging from the more recent manifestations of

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