《figures and descriptions of Canadian organic remains》

CHAPTERⅠ5

INTRODUCTION5

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 Quenstedt5

Their first reference to Poly-piaria ; the supposed affinity of Graptolites to the larv? of Echinoderms6

The name Graptolithus first established7

What forms are properly referable to the genus Graptolithus7

Dendrograptus， its mode of growth， and gradations through Callograptus to Dictyonema10

Forms of some Graptolites similar to the recent genus Crisia13

Forms with diverging stipes14

Doubly serrate forms (Diplograptus)15

Phyllograptus， Retiograptus Retiolites， Rastrites16

Thamnograptus ; Inocaulis， and its affinities to Graptolites18

Ⅱ. The central or basal portions of Graptolites19

The radicle or initial point19

The funicle19

The central disc20

Ⅲ. Nature and parts of the stipe21

The solid axis21

The common canal23

The cells， cellules， or calycles ; their form and mode of development24

Their similarity to the recent genera of Hydroid?25

Cell-walls， their double appear-ance and structure27

Exeavated cells27

Their internal structure28

Cells in Retiolites. Apertures of cells in some species of Graptolites ; in Dendrograp-tus29

The cells of Dictyonema29

Ornaments of the test in different genera and species30

Ⅳ. Mode of reproduction and development in Graptolites， when first made known32

Different forms of germs， and their reference to species34

Reasons for sup-posing that the diprionidian forms always existed as simple stipes36

Develop-ment of cells in different genera37

Ⅴ. Mode of existence38

Simple or compound forms ; floating or fixed forms39

Ⅵ. General characters of the Graptolitid?40

The condition of specimens heretofore described. Genera and sub-genera proposed : reasons for and against retaining these40

Diplograptus to what forms the term is properly applied44

Peculiar characters of D. putillus44

Biserrate forms which are properly separable from Diplograptus45

The genus Retiolites46

Differences observed between Euro-pean and American specimens47

Retiograptus and other genera considered47

Synopsis of the genera of Graptolitid?50

Ⅶ. Geological and geographical distribution of the Graptolitid? in the rocks of Canada and the United States. Equivalency of the American graptolitic beds with those of Europe51

Mr. Barrande's opinion of the age of the graptolitic schists in Northern Europe and in Bohemia. The graptolitic beds in New York. Discovery ?of a Graptolite in the Potsdam sandstone. The graptolitic beds of Canada52

Graptolites of the Utica slate and the Hudson-River formation53

Table showing the vertical distribution of the genera of the family of Graptolitid?55

Table showing the geological distribution of the species of Graptolitid? in Canada and the United States56

Ⅷ. Historical notice of the genus Graptolithus59

CHAPTER Ⅱ65

Ⅰ. Synopsis of the species of Graptolitid? from the Quebec group described in this Memoir65

Ⅱ. Descriptions of the species of Graptolitid? illustrated in this Memoir under the following genera :68

GRAPTOLITHUS68

DIPLOGRAP TUS109

CLIMACOGRAPTUS111

RETIOLITES113

RETIOGRAPTUS115

PHYLLOGRAPTUS118

DENDROGRAPTUS126

CALLOGRAPTUS133

DICTYONEMA136

PTILOGR APTUS139

THAMNOGRAPTUS141

SUPPLEMENT143

Descriptions of Graptolites from the Utica slate， introduced for comparison and illus-tration143

INDEX149

PLATES153