TABLE OF CONTENTS. ix 



Class Crinoidea 488 



Literature, 493. Artificial Key to the Genera, 494. Order I, 

 Larviformia, 498. Order TI, Fistulata, 500. Order III, 

 Camerata, 515. Order IV, Flexibilia, 562. Order V, Artic- 

 ulata, 567. Incertae Sedes, 569. 



Branch Asterozoa 570 



Class I. Ophiuroidea 570 



Order I, Euryaleae, 570. Order II, Ophiureae, 571. 



Class 2. Asteroidea 571 



Subclass I, Encrinasteriae, 571. Subclass II, Euasterise, 572. 



Branch Echinozoa 572 



Class Echinoidea 572 



Literature, 575. Key to the Genera, 576. Subclass Palae- 

 echinoidea, 578. Order Perischoechinoida, 578. Subclass 

 Euechinoidea, 585. Order Cidaroida, 585. Order Diadema- 

 toida, 586. Order Holectypoida, 589. Order Clypeastroida, 

 590. Order Spatangoida, 595. 



Appendix A. Summary of North American Stratig- 

 raphy. Tables of Geological Formations 604 



General Table of Geological Formations 604 



A. The PalcEOZoic Systems 605 



I. The Cambric System, 605. II. The Ordovicic System, 613. 

 III. The Siluric System, 621. IV. The Devonic System, 628. 

 V. The Mississippic System, 633. VI and VII. The Carbonic 

 and Permic Systems, 638. 



B. The Mesozoic Systems 649 



VIII. The Triassic System, 649. IX. The Jurassic System, 651. 

 X. The Comanchic System, 652. XL The Cretacic System, 653. 



C. The Cenozoic or Tertiary Systems 656 



XII. The Eocenic System, 656. XIII. The Oligocenic System, 

 658. XIV. The Miocenic System, 660. XV. The Pliocenic 

 System, 661. 



D. The Psychozoic or Quaternary Systems 662 



XVI. The Pleistocenic System, 662. XVII. The Holocenic or 

 Recent System, 663. 



Appendix B. Faunal Summary. Tables Showing the 



Distribution of the Species Described 664 



I. Cambric Faunas 664 



