316 
TATE: YORKSHIRE PETROLOGY. 
Explanation of Plates. 
Plate xiv. 
Fig. 
24. 
Mica-syenite. Above the waterfall Helmsgill 
X 
2. 
25. 
Brown mica : hexagonal plates, corroded 
X 
50. 
26. 
Do. do. with pale periphery... 
X 
30. 
27. 
Do. rectilinear plate, with rugged boundary 
X 
20. 
28. 
Do. do. broken and displaced 
X 
20. 
29. 
Do. do. do. 
X 
20. 
30. 
Do. do. do. 
X 
15. 
31. 
Do. do. younger generation . . . 
X 
50. 
32. 
Do. do. do. 
X 
50. 
33. 
Felspar with kaolin following cleavage 
X 
15. 
34. 
Felspar pseudomorphs mimicking olivine 
X 
50. 
35. 
Do. do. 
36. 
Do. do. 
37. 
Porphyritic inclusion of mica and sphene . . 
Do. Titaneferrite and leucoxine at x x 
X 
10. 
38. 
Mica-plate, at x in Fig. 37 : Labyrinthic structure 
X 
50. 
39. 
Hornblende pseudomorph : mineral not identified . . . 
Plate XV. 
X 
10. 
40. 
Mica-trap. Lowest dyke Helmsgill 
X 
50. 
41. 
Do- " Microlithenfilz" 
X200. 
42. Do. Microlites based on mica-plate ... x 200. 
the structure and affinities of lepidodendon. 
by thomas hick, b.a., b.sc, demonstrator and assistant lecturer 
IN BOTANY, THE OAVEN's COLLEGE, MANCHESTER ; 
AND WILLIAM CASH, F.G.S., F.L.S., F.R.M.S. 
The researches of Witham, Binney, Carruthers, and above all, 
the classical investigations of Williamson, into the histology and 
anatomy of Lepidodendron have made us so familiar with the chief 
structural features of the plants belonging to that genus, that it can 
scarcely be regarded as premature if an attempt be now made to 
