Johnson — Spermolithus Devonicus and other Pteridosperms. 253 



EXPLANATION OF PLATES. 

 (The illustrations are from photographs taken by H. Patterson.) 



Plate IX. 



Fig. 



1. Leaf-base of Avchmopteris hibernica, showing vascular stipules and 



pinnules. 



2. Another leaf-base of A. hibernica. showing grooves on detached surface. 



3. Side view of leaf-base of A. hibernica. 



4. Stem of A. hibernica, showing dilatation of base of leaf-stalks. 



5. Stem of A. hibernica (A) with attached leaves. B, slab showing a 



detached leaf- base of A. hibernica, placed in position for comparison 

 with A. 



Plate X. 



1. Stem of A. hibernica, showing the forking leaf appendages, &c. 



2. Stem of A. hibernica, showing the more distant, slenderer leaf-bases in 



the upper part. 



3. Adventitious loots arising from the stem of A. hibernica. 



4. Stem of A. hibernica, showing the pendulous collapsing and delaminated 



leaf -stalks. 



5. A portion of a leaf of A. hibernica, showing dilations and curvature of 



base of rachis of pinnfe. 



Plate XL 



1. Fertile palmatisect pinnule of A. hibernica, detached. 



2. A similar pinnule attached to Archwopteris stem (upper left-hand). 

 3 a, b. Two views of isolated spore of A. hibernica (50,u in diameter). 



4. Slab showing the speck-like microsporangia of Sperraolithm devonicus. 



5. An isolated microspore of S. devonicus. 



6. A dehiscing microsporangium of S. 'devonicus, slightly enlarged. 



SCIENT. PROC. R.D.S., VOL. XV., NO. XXIII. 2 S 



