Vol. 50.] ' DEVONIAN ' SERIES IN PENNSYLVANIA. 739 



but giving prominence to the curved ridges of clayey material sticking 

 out around the rim of the cone in a manner suggestive of vertica. 

 or lateral squeezes amongst the cones. 



Fig. 14. Transverse section (polished surface) of an abnormal development of 

 the horizontal dark clayey rings of figs. 11-13, showing a fibrous or 

 laminated structure. From the Lower Productive Coal Measures, 

 Beaver Falls, Western Pennsylvania. 



Fig. 15. Slightly magnified portion of a micro-slide of Portage cone- in-cone 

 (inverted layer), exhibiting miniature faulting in a dark layer of sedi- 

 ment passing through the conic cake. The dark spots are various 

 portions of the same form as that shown in PI. XXXV. fig. 24. From 

 Northeast, Pennsylvania. 



Fig. 16. Much reduced drawing of parts of three heights of inverted cone-in- 

 cone affected by a local swelling (a concretionary ridge?) of the 

 central or nucleal stratum of the conic mass of which they form a 

 portion. This also shows slight faulting of the cones, clearly a result 

 of lateral pressure in connexion with the swelling above. Reduced 

 about 8 times. 



Fig. 17. Cone-in-cone, with truncated apices. 



Fig. IS. Conic scales, somewhat distorted, with their apices bent backward and 

 disarranged. 



Fig. 19. Horn-shaped cone-iu-cone, with slickensided surfaces. 



Fig. 20. View of a complete cone, looking at its apex, showing the arrangement 

 of the pointed ends of the component conic scales forming the apex. 



Fig. 21. Markings on the polished surface of a transverse section of a good 

 cone, about ^ inch from the base of the cone. This shows the compo- 

 nent conic structure and some of the dark specks (see PL XXXV. 

 fig. 24). _ 



Fig. 22. Perspective view of a bit of argillaceous shale, on one flat surface of 

 which a singular concentrically-arranged scalariform structure of the 

 same shale was revealed. This may possibly represent the impression 

 of the base-surface of part of a layer of cone-in-cone. 



Fig. 23. Reproduction from a photograph of part of two inverted conic cakes 

 seen in cross fracture. The upper layer of cones is much confused, 

 crumpled and slickensided. A thin band of calcareous sandstone 

 separates the two layers of cones. 



Q. J. G. S. F/o. 200. 3 e 



