576 ME. T. UELXAPvD ETADE ON POST-GLACIAL BEDS [Aug. 1 898, 



The foregoing analysis shows how extremely minnte the grains 

 of this material were, as only •0093 of the whole remained in 

 the sieve-meshes, while 61 per cent, of the whole passed off in the 

 floatings and was not even deposited by subsidence. 



The material in the -^^-inch mesh consisted of shell-fragments, 

 two minute helical shells, some spore-cases, a few grains of sand 

 and globular or pear-shaped aggregates of calcite-crystals. The 

 ■jL-inch mesh material was largely composed of similar but smaller 

 calcit3-g rains, with some very rounded and smoothly worn quartz- 

 grains, together with very thin and highly glazed shell-fragments. 

 The material from the yi^-inch mesh contained a larger proportion of 

 quartz-grains, some highly rounded and polished, many of ihe normal 

 calcite-grains, a fair proportion of shell-fragments, flakes of mica, 

 some foraminifera, and a fe^' vegetable fibres. The shell-fragments 

 consisted of both flakes and portions of highly curved helices. The 

 material that passed the ^ ^Q-inch mesh and was deposited by sub- 

 sidence cor. si -ted of 3S per cent, of the whole. It was a grey powder, 

 mostly made up of clear quartz-sand in very even-sized grains. 

 Some of these were as roanded and hishlv polished as any that 

 I have ever seen. Two of these grains I reraaiked specially, 

 as they are less than tt^ inch in diameter on the longer axis. 

 and under the microscope are seen to be most beautifully rounded 

 and polisher! : they are, in fact, microscopical pebbles. 



Dr. G. J. Hinde kindly examined specimens of these sedimentary 

 washings for me ; of the yJ^-^-inch mesh material he says : — ' The 

 sample contains a very few broken fragments of spicules of t-etracti- 

 neliid siliceous sponges, now white or changed into crystalline silica, 

 and with Ihe axial canal filled with foreign material, and they evi- 

 dently originate from Cretaceous beds. The finer sample (-that which 

 passed the yJ-^inch mesh) contains broken fragments of acerate and 

 pin-shaped spicules of monactinellid sponges, very fresh-looking, and 

 they might well belong to forms still living or to those in Tertiary 

 beds ; they are certainly more recent than the white crystalline 

 spicular fragments.' 



A parcel of this clay was submitted to Mr. Joseph bright, of 

 Belfast, to whom I am much indebted for the thorough examination 

 which he has made of the foraminifera. The following is his 

 report : — 



Argile des polders superieure. 



Weight, f''6 oz. trey. After washing : fine, "8 oz. ; coarse, 'OOi oz. Oue 

 angular stone. Foraminifera plentiful. 



I/IST OF FcRAMiyiFERA. 



*TeTfuIcria glchuhm, Ehr.i H ure. 



Boiivina -plkata, dOrb. Ecre. 

 *Loffena ff'oboea (Mont.). Very rare. 



5, Wil/iamsoni, Alccck. Very rare. 



1 [The species oFforaii;ii::fera marled with rn asterisk in this and subsequent 

 lists in the rresent paper hare been alreac'y rpcurded from similar deposits 

 at Ce'erd which 8p]iear to be classified toge;her rs Argile des polders. 

 See Y; n den iBioeck, Ann. Sec. Beig. Microsc. \oi. iii (1677) pp. cr?i-cx3d. — 

 T. M. E.] 



