﻿CONTENTS. 



Prefatory Note ''•■ 



INTRODUCTORY (pages 3-48). 



Chapter I. — Discoveries and Collections 5-20 



American localities and types 5" 11 



Maryland 5" 6 



Isolated or little known localities 6-7 



Discovery of cycads in the Black Hills 7-10 



Cycad localities of central Wyoming 10 



California 10 



Occurrence and distribution of North American fossil cycads 



in time n 



European cycads, discovery of various historic types 12-16 



Cycads of India 16-18 



Old World Types of Cycadeoideae, the horizons in which they occur, 



and the museums in which they are located 18-20 



Chapter II. — Preservation and External Characters 21-44 



Varying conditions of fossilization and resulting trunk forms 21-29 



Local conditions of preservation 2 3~ 2 5 



Rare occurrence of conditions requisite for mineralization of 



cycadean trunks 26 



Trunk forms due to compression during or after fossilization. . . . 26-29 



Trunk types 29-44 



Low growing unbranched trunks 3 x -33 



Short columnar trunks 33 



Columnar trunks distinctly more than one meter high 33-36 



Branching trunks 36-44 



Resume 44 



Chapter III. — On the Methods oe Section Cutting 45-48 



VEGETATIVE FEATURES (pages 45-104). 



Chapter IV. — Trunk Structure 51-80 



Armor 5 1-66 



Ramentum 51-55 



Leaf bases 55-68 



Outer features and arrangement 55-59 



Leaf-base bundle grouping 59-64 



Leaf-base bundle structure 64-66 



Cortex 66-74 



General features 66-68 



Cortex of trunk 393 68-74 



Xylem zone 74" 77 



Phloem 76-77 



Medulla 77-7$ 



Cycadeoidea Jenneyana and C. ingens 78-80 



V 



