EXPLANATIONS OF PLATE XVI, continued. 

 Phyllograptus Anna, page 124. 



Fig. 11. A specimen with the folia obliquely compressed. 



" 12, 13, 14. Individuals showing some varieties of form. The specimens have all 

 been so imbedded that one of the folia has been torn away in the separated 

 laminae of shale, leaving an axis marked by the bases of its cellules. 



" 15. An enlargement of a specimen which has one of the laminae vertically im- 

 bedded, and shows the bases of the cells as they recede from the axis. The 

 markings at the sides are from the impressions of the folia, except a small 

 fragment of one remaining on the left-hand side of the figure. 



" 16. An enlargement from a specimen where the two lateral folia remain, showing 

 the bases of the cells of the folium which has been broken oflF, in the 

 separated laminae of slate. The surface is distinctly striated. 



Phyllograptus angustifolius, page 125. 



Fig. 17. A small and comparatively wide specimen, with a distinct linear axis, but 

 without evidence of cellules. 



" 18. A more elongate specimen, with distinct axis, with a darker line in the centre. 



" 19, 20, 21. Varieties of form and proportion. The specimen fig. 21 is the largest 

 observed. 



This species is placed under Phyllograptus from its similarity in form to 

 others of the genus, although evidence of the quadruple division has not 

 been established. The want of parallelism of the margins, and the sub- 

 elliptical form would, I conceive, be sufficient to remove it from the genus 

 Diplograptus. 



Graptolithds Bigsbyi, page 86. 



Figs. 22, 23, and 24 illustrate a common condition of this species, where two of the 

 divisions show the lateral faces, while the non-celluliferous edge of a 

 third division is seen lying nearly vertically in relation to these. The 

 fourth division has been broken oflf in the separated film of slate. 



" 25. A specimen showing the lateral faces of two divisions. Below these, in the 

 shale, are seen the non-celluliferous edges of the two other divisions. 



" 29 and 30 show a still closer arrangement of the parts, and the contiguity of 

 the non-celluliferous edges at the apices, which are scarcely perceptibly 

 separated in the shale. 



" 26. An individual where the apices of the divisions are in contact, either conjoined, 

 or accidentally so placed, with a narrow space in the centre. In obscure 

 specimens it is difficult to separate such forms from Phyllograptus. 



" 27. An individual where the divisions are equally spreading : one of them pre- 

 serving only the base of the stipe. 



" 28. The same enlarged. 



