I t is not without misgiving that I venture to offer to the notice of the Geological Society the following Memoir—justified in its production only by the fact that, during a residence of some years in Northamptonshire, I have been enabled, in the intervals of much other occupation, to acquire some familiarity with the geology of my own neighbourhood, and to make a collection of local fossils, which, in deference to “the inexorable logic of facts,” I cannot but anticipate will prove of greater importance, as illustrative of the geology of the district, than any paper of which I may be the author. It is fortunate for me that, as compared with some other districts, little has been written upon that of which I treat. The earliest geological notice of the locality is, I believe, to be found in Conybeare and Phillips, 1822; but it must not be forgotten that Morton, in his quaint and, for his time, learned, “Natural History of Northamptonshire,” published as early as 1712, described and figured, generally with accuracy, numerous fossils now as then obtainable from the geological formations of the county, including a Trigonia of a species not yet recorded as occurring in equivalent beds in other districts, and which Dr. Lycett has done me the honour of distinguishing by the name of T. Sharpiana . A “Notice of the Geology of the Neighbourhood of Stamford and Peterboroug,” by the late Capt. Ibbetson, F.G.S., and Mr. (now Professor) Morris, F.G.S., was published in the ‘Transactions’ of