1849.} CARPENTER ON THE STRUCTURE OF NUMMULITES, ETC. 21 



vey,' are not always to be found on specimens. The best examples 

 which I have seen of these extraordinary characters, are two fossils 

 in the museum of the Leeds Philosophical Society. These I first 

 observed in company wdth the late Mr. Bowman in 1839, when we 

 were both much struck with their appearance, and that gentleman 

 procured drawings of them, of which the present are reduced copies. 

 The specimens are composed of a fine-grained sandstone, and I be- 

 heve they were found in the coal-measures near Bradford, Yorkshire. 



Figs. 5 and 6 represent 

 an under and a side view of Fig. 5. Fig. 6. 



the larger of these fossils. 

 The greatest breadth mea- 

 sured across the suture is 

 2 feet 2 inches. The parts 

 of the roots remaining are 

 mere stumps, and show no 



true characters of either Sigillaria or Stigmaria, bat are marked with 

 the irregular lines so generally found on decorticated specimens of large 

 Sigillariee, just like those on the Dixon Fold and St. Helen's trees. 



Figs. 7 and 8 represent 

 the under and side views Fig. 7. 



of the smaller of these 

 specimens. The greatest 

 breadth at the base across 

 the suture is 14 inches. 

 As part of the roots of 

 this specimen remain, we 

 see the same system of 

 dichotomizing which was 

 noticed in the Dixon Fold 



and St. Helen's trees. At the extremities of both 

 roots are the usual areolae with a little elevation in 

 the centre and the convex corrugated lines so com- 

 mon to Stigmarige. 



Fig. 9 gives a tolerable idea of the appearances 

 which in my opinion prove the specimen without 

 doubt to be a Sigillaria. 



Fig. 8. 



2. 071 the Microscopic Structure of Nummulina, Orbitolites, 

 and Orbitoides. By William B. Carpenter, M.D., F.R.S., 

 F.G.S. 



About five years since, I was requested by my friend Mr. S. P. 

 Pratt to endeavour to determine by microscopic examination the cha- 

 racter of certain discoidal bodies, varying from about four to ten lines 

 in diameter, which he had found in great abundance in the nummu- 

 litic deposits of Biaritz, and the nature of which could not be resolved 

 by any ordinary means. Their circular form and limited dimensions 

 seemed to indicate their relation either to the group of Nummulites 



