There is room for considerable difference of opinion as to the limit of the order Pandaneœ or “Screw-pines.” However extended it is made there can be no doubt that Nipa has closer affinities with the palms than with the screw-pines. I shall therefore exclude the remarkable fruits from the Lower Eocene of Sheppy to which Brongniart applied the name Pandanocarpum, altered afterwards by Bowerbank in accordance with the more precise determination of the affinities of the fruits to Nipadites, a change in which Brongniart aequiesced.

I Propose now to pursue my subject by describing in some detail a series of typical examples of the principal groups of agatescent minerals; noting, as we proceed, the circumstances in each which appear to afford proper ground for future general classification.

The Heudeshope beck is a small feeder of the Tees, running swiftly down a steep valley into the main stream, at Middleton Teesdale. It is wholly in the lead-measures (Carboniferous limestone), which are here nearly horizontal, undisturbed by trap, and shew only a few faults, so small as not to affect the surface. The great Teesdale fault operates on the other side of the main valley. The Heude beck flows north and south. Its source is in the table-land, forming the water-shed, between Weardale and Teesdale, whence four or five streams issue in different courses. It is unobscured by the drift beds, which characterize the opposite lower slopes of the Tees valley. It is excavated down to the solid rock, the banks have been quite undisturbed by cultivation. It passes through forty-three distinct alternations of grit, shale, and limestone, to each-of which the miners have given a distinct name; it falls about 1,000 feet in the six miles of its course, In the hope that a tramp down by side of its brawling rivulet, during the short hours of a winter day, might illustrate some theory of valley-formation, I devoted one of the last days of the year to the task.

From the proposition of Professor Forbes, that a species once extinct never reappears, it follows that when a species recurs, it must have existed elsewhere during the whole of the time occupied by the deposition of the strata between the deposits containing it. In viewing the distribution of species through the cheif stages of the Lower Cretaceous system, it appears that the same species reappear when there is a recurrence of the same or similar physical conditions,—the Neocomian and Albian clays having more species in common than the intervening Aptian; and the Aptian and Cenomanian sands, being more closely allied than the intervening Albian clay. An examination of the latter, at Folkestone, appears to allow of its being divided into eleven lithological stages or beds which have been more or less recognized by all geologists and fossil collectors who have visited the district. To these beds provisional names have been assigned expressive either of their colour, position, or characteristic fossils. But in tracing all the recurring species from their genesis in one stratum to their extinction in another, these beds are found to have no great palæontological value, but to resolve themselves into two groups divided by a junction bed, in the same way as the “junction bed” separates the Albian from the Upper Aptian. Beds I. to III. forming an Upper, beds V. to X. a Lower Albian, beds IV. and XI. being the two phosphate junction beds,

The discovery of fossil insects in North America is of very recent date; even now, scarely a hundred specimens have been brought to light, and they have occured, with few exceptions, as solitary individuals. The Reports of State and provincial geologists, which have added so richly to our knowledge of the palæontology of North America, have hardly mentioned these fossils. As descriptions of them are scattered through many publications—doubtless difficult of access to English geologists— and as most of the specimens referred to have passed under my eye, I have prepared this general resumé of what is known and have accompanied it with critical remarks.

Near the city of Ripon, on both sides the river Ure, but more particulary on the eastern side, there are a great number of natural pits, probably fifty or sixty, the origin of which appears to be very obscure.