A flint cast of a Mytilus has been obtained from the gravel of Barnwell, near Cambridge, by Mr. Percevall, B.A., Trin. Hall, and entrusted to me for description.

Form elongated and narrow, attenuated anteriorly, with valves deep, and longitudinally striated. The anterior outline of the lips is straight, that of the posterior side a gentle curve, which is somewhat straightened towards the apex. The shell is about three times and a half as long as wide, and widest below the middle. The lateral outline of the valves is lanceolate, the greatest height being in the anterior third.