TABLE OF CONTENTS.
Reading edition
Historical review 17
Part I. The appendages of trilobites 20
Terminology 20
The appendages of Neolenus 21
Historical 21
Neolenus serratus (Rominger) 21
Cephalon 21
Thorax 22
Pygidium 23
Epipodites and exites 23
Description of individual specimens 23
Restoration of Neolenus 30
Nathorstia transitans Walcott 31
The appendages of Isotelus 32
Historical 32
Isotelus latus Raymond 34
Isotelus maximus Locke 35
Restoration of Isotelus 37
Isotelus gigas Dekay 37
Isotelus arenicola Raymond 39
The appendages of Triarthrus (see also Part IV) 39
Triarthrus becki Green 39
Historical 40
Restoration of Triarthrus 42
Relation of cephalic appendages to marking on dorsal surface of glabella 43
Anal plate 44
The appendages of Ptychoparia 45
Ptychoparia striata (Emmrich) 45
Ptychoparia cordilleræ (Rominger) 45
Ptychoparia permulta Walcott 45
The appendages of Kootenia 46
Kootenia dawsoni Walcott 46
The appendages of Calymene and Ceraurus 46
Historical 46
Comparison of the appendages of Calymene and Ceraurus with those of Triarthrus 47
Spiral branchiæ 48
Ventral membrane 50
Appendifers 51
Calymene senaria Conrad 52
Cephalic appendages 52
Thoracic appendages 53
Pygidial appendages 54
Relation of hypostoma to cephalon in Calymene 55[12]
Restoration of Calymene 56
Calymene sp. ind. 56
Ceraurus pleurexanthemus Green 57
Cephalic appendages 58
Thoracic appendages 59
Pygidial appendages 59
Relation of hypostoma to cephalon 59
Restoration of Ceraurus pleurexanthemus 60
The appendages of Acidaspis trentonensis Walcott 61
The appendages of Cryptolithus (see also Part IV) 61
Cryptolithus tessellatus Green 61
Restoration of Cryptolithus 62
Summary on the ventral anatomy of trilobites 64
Comparison of appendages of different genera 64
Coxopodite 64
Cephalon 64
Thorax 66
Pygidium 67
Caudal rami 68
Homology of cephalic appendages with those of other Crustacea 69
Functions of the appendages 70
Antennules 70
Exopodites 70
Endopodites 71
Use of the pygidium in swimming 72
Coxopodites 74
Position of the appendages in life 74
Part II. Structure and habits of trilobites 77
Internal organs and muscles 77
Alimentary canal 77
Ceraurus pleurexanthemus 79
Calymene senaria 80
Cryptolithus goldfussi 80
Summary 81
Gastric glands 82
Summary 84
Heart 85
Illænus 85
Ceraurus and Calymene 85
The median "ocellus" or "dorsal organ" 86
Nervous system 89
Various glands 89
Dermal glands 89
Renal excretory organs 90
Reproductive organs 90
Panderian organs 90[13]
Musculature 91
Flexor muscles 92
Extensor muscles 92
Hypostomial muscles 94
Eyes 96
Summary 97
Sex 98
Eggs 98
Methods of life (See also under "Functions of the Appendages") 98
Habits of locomotion 99
Food and feeding methods 103
Tracks and trails 104
Part III. Relationship of the trilobites to other Arthropoda 106
Crustacea 106
Branchiopoda 106
Burgessia bella Walcott 108
Waptia fieldensis Walcott 108
Yohoia tenuis Walcott 109
Opabina regalis Walcott 109
Summary 109
Copepoda 110
Archicopepoda 111
Ostracoda 112
Cirripedia 113
Malacostraca 113
Phyllocarida 113
Syncarida 114
Isopoda 114
Marrella splendens Walcott 115
Restoration of Marrella 116
Arachnida 117
Trilobites not Arachnida 117
Merostomata 119
Sidneyia inexpectans Walcott 119
Emeraldella brocki Walcott 119
Molaria and Habelia 120
Araneæ 121
Insecta 122
Chilopoda 123
Diplopoda 124
Primitive characteristics of trilobites 125
Trilobites the most primitive arthropods 125
Limbs of trilobites primitive 125
Summary 128
Number of segments in the trunk 128
Form of the simplest protaspis 132[14]
Origin of the pygidium 134
Width of the axial lobe 137
Presence or absence of a "brim" 137
Segmentation of the glabella 137
Summary 138
The simplest trilobite 138
Naraoia compacta Walcott 139
The ancestor of the trilobites, and the descent of the Arthropoda 140
Evolution within the Crustacea 142
Summary 144
Evolution of the Merostomata 146
Evolution of the "Tracheata" 147
Summary on lines of descent 147
Final summary 151
Part IV. Description of the appendages of individual specimens 152
Triarthrus becki Green 152
Cryptolithus tessellatus Green 158
Bibliography 163