736 MR. W. S. GRESLEY ON CONE-IN-CONE IN THE [NOV. 1 894, 



notice of it, but the illustrations which accompany his paper do not 

 seem to be of specimens sufficiently well-developed to display the struc- 

 tures referred to. namely, those brought out in PL XXXVI. figs. 1 1 

 and 12. I also venture to believe that my illustrations (PI. XXXV. 

 figs. 7 and 8), which show the curiously wrinkled or corrugated 

 surfaces of the bases of the cone-in-cone, are new in this connexion. 

 Assuming, then, that the all-important characteristics and sufficient 

 detail of the cone-material have been grasped and fairly under- 

 stood — for so complex a structure is by no means easy to describe, 

 however easy it may be to illustrate, — we may now proceed to 

 summarize the observed facts and draw deductions therefrom. 



4. Conclusions. 



(1) The perfectly normal and practically unchanged and undisturbed 



condition of the cone-in-cone-bearing Portage Beds in North- 

 western Pennsylvania furnish conclusive evidence that this 

 cone-in-cone is there in place, and moreover that it was formed 

 since and not pari passu with the enclosing strata. It is there- 

 fore a secondary product, and a product of alteration. 



(2) The nests or multiple-heights (one layer above another) of the 



conic material, from their very position or lie in the strata, 

 show that they were formed simultaneously; but how long 

 the process took, at what depth it operated, and whether it is 

 going on still or not, we do not know. 



(3) That each and every individual layer, as well as nest of cones, 



has been formed from practically the same materials and in the 

 same manner is sufficiently obvious. 



(4) The cone-forming conditions (whatever they were) evidently 



had an affinity for certain horizons in the Portage series, and 

 were also such that the cone-formations were originated more 

 in one place than another — they seem to be numerous in some 

 places, scarce or absent in others, on the same stratigraphical 

 horizon. 



(5) The cone-in-cone avoids the harder and more sandy layers, but 



does not occupy the whole thickness of the shaly layers inter- 

 bedded, in very frequent alternations, with the sandy ones. 

 The core or nucleal layer of the conic masses certainly con- 

 tained the ' germ,' so to say, of the structures (probably some 

 fossil) ; and, as it contains a considerable quantity of calcium 

 carbonate, which outside of the conic layers is absent, and 

 which also pervades other arenaceous laminae that have been 

 incorporated in the ' unconed ' parts of the structure, it is evident 

 that lime was an essential agent in the phenomena. 



(6) The swelling which occasionally accompanies cone-in-cone is 



probably due to the acquisition of lime from without by the 

 cones as they were forming, — a process which resulted in a 

 thrusting- aside vertically of the enveloping layers, in a manner 

 often observable in connexion with Coal-Meaaure nodules, and 

 with nodules of marcasite and pyrites in coal. 



