While engaged in the course of my duties in arranging the specimens collected for the Rock Collection in the Museum of Practical Geology, my attention was attracted by a chalk of unusual character. The specimen was collected by John Rhodes, when the second edition of the “Geology of London” (Memoirs of the Geological Survey) was in preparation, from an old pit at the Lodge of Taplow Court, the seat of W. H. Grentfell, Esq. By permission of the Director-General, I examined the pit, and made the following descending section:— Lodge Pit, Taplow Court . ft. in. Soft white chalk, top not seen 12 0 passing down into Brown chalk with Ostrea acutirostris , Nilss., Belemnifella quadrata , Defrance (both abundant), Echinocorys vulgaris , Breyn., and Cidaris sceptrifera , Defrance, about 8 0 White chalk traversed by numerous tubes and cavities filled with brown chalk ; a hard and blocky top, forming a marked floor to the brown chalk above 3 0 White chalk, mostly inaccessible, and not examined in detail 14 0 White chalk with scattered brown grains 2 6 passing down into Brown chalk, about 4 0 Hard crystalline chalk with nodular structure and greenish markings (like Chalk Rock), about 1 0 White chalk, piped with brown chalk as above 1 10 A sandy brown layer 0 0½ White chalk, piped with brown chalk 2 6 White chalk to the bottom of the pit, the first flints occurring 12 feet below the lower band of brown chalk 15 0+ At the top of the