Sir H. Howorth — Glacial Gravels, etc., of E. England. 533 



It is consequently proposed that in future, as far as the first three 

 are concerned, the term aptychus be omitted, the fossils being named 

 after the several Belemnites of which they form a part. 



EXPLANATION OF PLATE XVI. 



1. Lateral view of guard of Belemnitella lanceolata, showing curve of alveolar 



margin, and the dark stain parallel to it. 



2. External view of Aptychus leptopkyllus, showing the smooth thickened ridge on 



upper and outer edge, and also laminated lower edge. 



3. Internal view of same, showing the curved lines of growth, and curved line 



produced by membrane on the lower outer edge. 



4. External view of largest specimen of Apt. leptopkyllus. 



b. Internal view of smallest specimen of Apt. leptopkyllus. 



6. Front view of Rhyncholite, the upper mandible of Bel. lanceolata. 



7. Lateral view of the same. 



8. External view of Aptychus Portlockii — the right perfect half, the left broken 



on inner edge. 



9. External view of an example of Apt. Portlockii ; the surface is nearly smooth, 



showing but few lines of growth. 



10. External view of a specimen of Apt. Portlockii, slightly broken on inner and 



lower edges ; lines of growth strongly marked. 



11, 12. Two small examples of Apt. Portlockii, the two halves united on the inner 



margin at an angle which corresponds with that of the alveolar cavity of 

 Belemnitella quadrata. 



13. Internal view of right side of Apt. Portlockii, showing regular lines of growth. 



14. Dorsal view of a part of guard of Bel. quadrata, showing the form of alveolar 



cavity and the curve of alveolar edges. 



15. Lateral view of the same. 



16. External view of a large specimen of Aptychus rugosus from the Upper Chalk, 



Norwich. 



All the illustrations of Bel. quadrata and Apt. Portlockii are magnified two 

 diameters, save Figs. 14 and 15, which, like the other figures, are of the natural size. 

 The specimens are in the author's cabinet, Vale House, Salisbury. 



II. — The so-called Middle Sands and Glacial Guavels op 

 Eastern England. 



By Sir Henry H. Howorth, K.C.I.E., M.P., F.R.S., F.G.S. 



IN a previous paper I have discussed the post-Tertiary Clays 

 of Eastern England. 1 In that paper I endeavoured to show- 

 that these clays, varying as they do in texture, composition, 

 and contents, mark a varying geographical distribution and sub- 

 stratum rather than a succession of changes in time ; that, so far 

 as we can tell, they are for the most part on the same horizon, 

 and interlock with each other, with occasional local overlaps ; while 

 they are united by one common element, namely, the presence of 

 certain foreign boulders of the same general type in them all. 



These clays are closely associated with largely developed beds 

 of sand and gravel, which present similar problems for solution, 

 and to some hitherto neglected features of which I should like to 

 call attention. Before turning to these sands, _ etc., I would, 

 however, add one or two additional facts and quotations in reference 

 to the clays in support of my former conclusion. In Norfolk 

 an attempt has been made to separate the so-called glacial clays 

 i Geol. Mag., October, 1896, p. 449. 



