Fisher^Roswell Hill Clay-pit, Ely. 407 



DESCRIPTION OF PLATES XVIII. & XIX. 



PLATE XVIII. 



Fig. \-\b. Terchraiula depressa, var. cyrta. 

 2-la. T. dcprcssa, Lamk. typical form. 

 Z-Zb. JF. ritomboidea, sp. n. 

 4. W. rhomboidea, large specimen. 

 5- 5a. T. extensa, Meyer. 

 6-6/>. T. Moiitoniana, d'Orb. 

 7-7*. T. sella, Sow. 

 8-8*. W. pseudo-jurensis, Leym. 

 9, 10, 11. W. pseudo-Jurensis, Leym. To show different forms. 



PLATE XIX. 



Fig. 1. T. prcelont/a, Sow. 



2-2*. T. Zankesteri, sp. n. 

 3-3«. T. Lankesteri, sp. n. jun. 

 4-4*. JF. mntabilis, sp. n. var. elliptica. 

 5-5a. W. mutabilis, sp. n. var. angusta. 

 6-6*. T. Mei/eri, sp. n. 

 7-7<'. T. microtrema, sp. n. 

 8-8«. T, microtrema, sp. n. 

 9. T. tamarindus, Sow. var. magna. 

 10-10*. JF. tamarindus, Sow. var. magna. 

 I have presented to the British Museum the specimens figured in illustration of this 

 and my former paper. — J. F. W. 



IV. — On Koslyn or Koswell Hill Clay-pit, near Ely.^ 

 By the Pev. 0. Fisher, M.A., F.G.S. 



ROSLYN or Eoswell Hill Clay -pit has long been a standing puzzle 

 to Cambridge geologists. I have visited it several times, and 

 have notes upon it made in 1853 and in 1856. I was there in 

 November, 18G6, having, by Professor Sedgwick's permission, the 

 the assistance of Mr. H. Keeping. 



The pit is probably well known to you. It covers several acres 

 of ground, and extends in a direction N.W. and S.E. The material 

 has been used for the purpose of making up the banks in the fens, 

 and the section is comparable to that of many natural cliffs. 



The northern side of the pit is occupied by horizontal Kimmeridge 

 clay, which is, or used to be, capped here and there by a thin 

 covering of Lower Green-sand. At the western end of the pit 

 Boulder-clay of a typical character abuts against the Kimmeridge 

 clay, the plane of junction running nearly east and west, and dipping 

 at a high angle under the Boulder-clay. The southern side of the 

 pit, as at present exhibited, shows a blueish grey Cretaceous clay, 

 flanked at either end by nearly vertical Chalk-marl, which becomes 

 somewhat argillaceous towards the eastern end of the pit. The 

 Chalk-marl and clay are evidently in true sequence. 



The question which I propose to discuss relates to the singular 

 collocation of these several beds. 



^ Bead before the Cambridge Philosophical Society. As this paper was somewhat 

 severely criticised by Mr. Seeley in our last jS^o. (p. 347), we gladly avail ourselves of 

 the author's permission to reprint it here. — Edit. 



