12 THE APPENDAGES, ANATOMY, AND RELATIONS OF TRILOBITES. 
Relation of hypostoma to cephalon in Calymene 55 
Restoration of Calymene 56 
Calymene sp. ind 56 
Ceranrus 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 tcssellatus 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 yy 
Internal organs and muscles JJ 
Alimentary canal JJ 
Ceraurus pleurexanthemus 79 
Calymene senaria 80 
Cryptolithus goldfussi 80 
Summary 81 
Gastric glands 82 
Summary 84 
Heart 85 
Illcenus 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 
