46 PEocEEDmrGS of the geological society. [Apr. 14, 



3. On a Fossil ^wcit found in the upper part of the Wealden De- 

 posits in SwAiiTAGE Bay, Isle of Puebeck. 

 By Jom^ Phillips, M.A., LL.D., F.R.S., Pres. G.S., &c. 



But few of the numerous fossil remains of Plants in the Wealden 

 and Purbeck deposits of the British Isles have as yet been completely 

 described. Perns, Equisetacece, Monocotyledonous plants, Coniferce, 

 Cycadaceoe, and Characece have been recognized by their leaves and 

 stems. But fruits are uncommon. One of these is cycadaceous — Za- 

 miostrobuSy and there are two undetermined Carpolithi*. 



To this short catalogue I am now able to offer one addition, taken 

 from a nodule of ironstone in the upper part of the Wealden beds, in 

 Swanage Bay, at the close of 1857. 



The general section of the strata near Swanage, on a line from 

 north to south, shows, in succession, the Portland rock, the Pur- 

 beck deposits, the Wealden, and the Cretaceous beds. For the 

 purpose of this notice, only Wealden groups require attention. 



The upper part of the Wealden, as seen very completely in the 

 Northern Cliffs of Swanage Bay, exposes about 700 feet of clays fre- 

 quently red or purple, less frequently blue, greenish, or very pale, 

 alternating with sandstones of different tiats, mostly soft and line- 

 grained, but sometimes hardened by irony impregnation, or modified 

 by admixture of pebbles. One band contains much lignite. 



In the upper part of this series, above every red or purple 

 bed, are alternations of sandstone and pale shale. In one of the 

 shale-beds is a course of small nodules of pyritous ironstone, one of 

 which yielded, on fracture, the fruit in question. It is a mass of bi- 

 sulphuret of iron, which threatened to fall to pieces ; but, having 

 filled its pores with Canada balsam, I hope it may be preserved. 



The specimen in question has the form of a compressed ellipsoid. 

 The longest diameter, which coincides with the axis of the fruit, has 

 a length of 0*8 inch, the other two diameters, measured at right 

 angles to this, equal 0*7 and 0*6 inch respectively. The terminal 

 surface is almost completely preserved, the other is only sufficiently 

 traced to show the general figure. The weU-preserved terminal 

 surface (fig. 1) exhibits a central ring-like prominence ; round this 

 is an obtusely conical surface, slightly granulated, with faint traces 

 of radiating strise. Bound this is a circle of oval prominences, 

 from each of which a conspicuous rib or keel proceeds, in a radiating 

 manner, toward the opposite surface, so as to resemble the meridian 

 of a globe. Eight meridional costas are clearly traced, occupying the 

 circuit of the fniit symmetrically ; six of the prominences at their 

 origin are completely seen, a seventh is traceable, and there is an 

 interval corresponding to another. Thus the fruit is ascertained to 

 have had eight ribs symmetrically disposed. 



Between two of the costal promiuences, on the flatter side of the 



* See Mantell's Geol. South-east of England, p. 246, and Bronn's Leth. Gteoh 

 pi. 28, fig. 6, for a representation of Carpolithus Mantelli, supposed by Brong- 

 niart to be the fruit of Clathraria Lyellii. 



