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LXXXVI. Observatiotis on some of the Fossils of the London 

 Clay, and in partimlar those Organic Remains 'which have 

 been recently discovered in the Tunnel for the London and 

 Birminsliam Railroad. By Nath. Thomas Wetheuell, 

 Esq., KG.S., M.R.C.S., 4c* 



Tj^ROM the number of railroads now in progress in dif- 

 ^ ferent parts of this country, and the necessary excavations 

 required in the making of them, there probably never was a 

 time more favourable to the researches of the geologist than 

 the present; and it is sincerely to be hoped that no spot will 

 remain untouched, the examination of which holds out a pro- 

 spect of adding to our knowledge of the strata of the earth. 

 It is my intention in the following memoir to notice more par- 

 ticularly those remains of the London clay which I have re- 

 cently collected from that portion of the London and Bir- 

 mingham railroad which passes in the immediate neigh- 

 bourhood of Chalk Farm. I shall, however, occasionally ad- 

 vert to discoveries made in other parts of this important and 

 highly interesting formation, which, having closely examined 

 it in different places, I find contains many minute and exceed- 

 ingly curious fossils, well worthy the attention of the naturalist. 

 Before proceeding to a detail of the organic remains, it may 

 be as well to give a short sketch of the relative position and 

 appearance of the clay here, although there may be no per- 

 ceptible difference from other places where this stratum has 

 been exposed. Immediately beneath the vegetable mould is 

 a thin bed of diluvium, containing a few bones of animals: and 

 below this is the London clay, which may be easily traced 

 along the line of road, from Chalk Farm to a field in front 

 of Mornington-place, Hampstead road. This portion pre- 

 sents to the eye a reddish or yellowish brown colour, with oc- 

 casional patches of blue. It is of a loose texture, and contains 

 septaria, casts of shells, selenite, and decomposing masses of 

 sulphuret of iron. In the tunnel, about GO feet below the most 

 elevated part of the surface, the clay assumes a dark bluish 

 brown colour, and is much more compact, akhough here and 

 there mixed with sand. The greater part of the organic re- 

 mains are procured from the depth of from 30 to 60 feet, and 

 very few have been seen in the septaria. A few days since 

 I observed at the top of Park-street, Camden Town, where 

 the men were working at the depth of 10 or 12 feet, a layer 

 of masses of septaria horizontally disposed ; this is of common 

 occurrence, and the septaria are sometimes of a veiy large 



* Read before the Camden Literary and Scientific Institution, April 26> 

 ] 836, find communicated by tlie Council of that Institution. 



