TABLE OF CONTENTS. 13 
Panderian organs 90 
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 
Burgcssia bella Walcott 108 
Waptia fieldensis Walcott 108 
Yohoia tenuis Walcott . . . 109 
Opabina regalis Walcott 109 
Summary 109 
Copepoda no 
Archicopepoda in 
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 
Aranese 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 
