PLATE XV. 



Equisetides Wrightiana.* 



Fig. 1. The stem, natural size. Copy after Dawson. 



2. A transverse section in outline. 



3. "Leaf of sheath." 



Cyclostigma affine. 



Cyclostigma affine — surface showing leaf scars. 

 " leaf-base, enlarged. 



ASTEROPTERIS NOVEBORACENSIS. 



Asteropteris noveboracensis, cross-section, natural size and enlarged. 

 . noveboracensis, portion enlarged, showing one vascular bundle. 



" portion enlarged twelve times, showing rays and vascular bundle. 

 " " stem restored in cross-section. 



" " scalariform vessels, xlOO. 



" " prosenchyma of outer cylinder, x40. 



" parenchyma of inner cylinder, x40. 

 In the above figures, a represents radii of axis, b cellular tissue of axis, c outer prosen- 

 chyma, d leaf -bundles. 



* Note (Fig. 1.) — The peculiar aspect and markings of this figure, as originally pub- 

 lished in the Quarterly Journal of the London Geological Society, led the writer to sus- 

 pect its relations to the Crustacea. Through the kindness of Mr. Wright, who procured 

 the loan of the specimen, I have had an opportunity of seeing the original, which is very 

 correctly represented in the figure. The body is not cylindrical, but broadly elliptical or 

 subovate, enlarging above. The ridges occur only upon one side, having a symmetrical 

 relation with the form of the body, while the other parts are free from them, and the 

 joints are overlapping. The form of this body, together with the character of the ridges 

 and the. finer surface markings, suggest its crustacean origin. The lateral scars have 

 probably been the points of attachment for spiniform processes as in Stylonurus. The 

 fragment represents two of the abdominal segments of a form not unlike Stylonurus, 

 though comparatively longer than in the ordinary forms of that genus, and in this 

 respect resembling Stimoaia. 



J. H. 



Fig. 4. ( 



Jyc 



5. 





Figs. 6, 



7. 



8. 



A 



9. 



" 



10. 



11 



11,12. 



' 



13. 



< 



14, 15. 



1 



