The Appendages, Anatomy, and Relationships of Trilobites
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 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