AT the request of Mr. H. Woods, F.R.S., I have examined a small series of Echinoids belonging to the Sedgwick Museum, Cambridge, collected by the late J. F. Walker from the sand-pits on Shenley Hill, near Leighton Buzzard. Mr. G. W. Lamplugh has sent me four additional specimens from the same locality. The matrix seems to be the same in all the examples except D, and agrees absolutely with a sample of the Limestone-lentides sent for comparison by Dr. F. L. Kitchin. The age of this Limestone is a subject of controversy (see Geol. Mag., January—March, 1920), and a critical analysis of its fauna seems the only means of deciding the issue. Unfortunately, most of the Echinoids are very indifferently preserved so that specific determination is often doubtful, and in some cases impossible.