TABLE OF CONTENTS. 
CHAPTER I. 
INTRODUCTION. 
§ I. Nature and form of Graptolites; formerly known only in fragments; regarded by 
early writers as of vegetable origin; their reference to Cephalopoda by Wahlen- 
berg, Schlotheim, Geinitz, and Quenstedt, page 5.—Their first reference to Poly- 
piaria; the supposed affinity of Graptolites to the larve of Echinoderms, 6.—The 
name Graptolithus first established, 7—What forms are properly referable to the 
genus Graptolithus, 7-8.—Dendrograptus, its mode of growth, and gradations 
through Callograptus to Dictyonema, 10-12.—Forms of some Graptolites similar 
to the recent genus Crisia, 13.—Forms with diverging stipes, 14.—Doubly serrate 
forms (Diplograptus), 15.—Phyllograptus, Retiograptus, Retiolites, Rastrites, 16. 
Thamnograptus ; Inocaulis, and its affinities to Graptolites, 18. 
§ II. The central or basal portions of Graptolites, 19.—The radicle or initial point, 19. 
—The funicle, 19.—The central disc, 20. 
§ III. Nature and parts of the stipe, 21.—The solid axis, 21—The common canal, 23. 
—The cells, cellules, or calycles ; their form and mode of development, 24.—Their 
similarity to the recent genera of Hydroide, 25.—Cell-walls, their double appear- 
ance and structure, 27.—EHxcavated cells, 27.—Their internal structure, 28.—Cells 
in Retiolites. Apertures of cells in some species of Graptolites; in Dendrograp- 
tus, 29.—The cells of Dictyonema, 29, 30.—Ornaments of the test in different 
genera and species, 30, 32. 
§ IV. Mode of reproduction and development in Graptolites, when first made known, 
32.—Different forms of germs, and their reference to species, 34.—Reasons for sup- 
posing that the diprionidian forms always existed as simple stipes, 36.—Develop- 
ment of cells in different genera, 37. 
§ V. Mode of existence, 38.—Simple or compound forms; floating or fixed forms, 39. 
§ VI. General characters of the Graptolitide, 40.—The condition of specimens heretofore 
described. Genera and sub-genera proposed : reasons for and against retaining these, 
40 —43.—Diplograptus, to what forms the term is properly applied, 44.—Peculiar 
characters of D. putillus, 44.—Biserrate forms which are properly separable from 
Diplograptus, 45.—The genus Retiolites, 46.—Differences observed between Huro- 
pean and American specimens, 47.—Retiograptus and other genera considered, 
47-50.—Synopsis of the genera of Graptolitide, 50. 
§ VII. Geological and geographical distribution of the Graptolitide in the rocks of 
Canada and the United States. Equivalency of the American graptolitic beds with 
those of Europe, 51.—Mr. Barrande’s opinion of the age of the graptolitic schists in 
Northern Europe and in Bohemia, The graptolitic beds in New York. Discovery 
