282 VI SIT TO THE MUSEUM OF P RACTICAL GEOLOG Y.

explained the method of registering and cataloguing th e enormousnumber of specimens which find their way to thi s great storehouseof the organic remains obtained by th e Officers of the GeologicalSurvey and others from th e British Sedimentary Rocks.

EXCURSION TO RIDDLESDOWN AND CROYDON.

APRIL 17TH, 1875.

D irectore-s-Cs us » E VANS, Esq., F .G.S.; and J . LOGANLOBLEY, Es q., F.G.S.

Leaving the train at Oat erhsm Junction station, Members hadbut a few yards to walk to th e fine section of the Upper Chalk atthe western extremity of Riddlesdown. At the foot of th esection, Mr. Lobley described generally the great Chalk for­mati on as displayed in England, and pointed out th e peculiariti esof this section. Professor Morri s, who was one of th e party,then described the conditions which must have prevailed duringth e period of the deposition of the Chalk, and explained ther ela tions of this formation to Cretaceous st rata occurr ing in theContinental area. Gradually ascending the Down, while proceed­ing eastward,the Members attained an elevation which enabled the mto obtain fine views of a por tion of the Chalk country, with itsfinely swelling hill s and riverless valleys, formed by the NorthDowns.

On reaching th e mouth of the half-made tunnel of the aban­doned Surrey and Sussex R ailway, the ardent geologists imme­diately entered th e excavation, and very assiduously examined th eChalk with it s nodular IUld tabular flint here exposed. Mr. CalebE vans, who has made the geology of this distri ct hi s own, andwho has, from his observations of th e various Chalk sections ofthis neighbourhood, obt ained sufficient evidence to enable him todivide the Chalk into pal roontological zones, explained that thebeds here exposed are th e " Upper Kenley Beds," containing anassemblage of fossils markedly different from the fau~a of thePurley Beds, higher in the seri es, and also from that of th e imme­diately underlying Lower Kenley Beds. While In oceramus Cuivieriis wantin g in th e Upp er K enley Beds, it is present in both thePurley Beds and th e Lower Kenley Beds. Holaster planus and

EXCURSION TO RIDDLllSDOWN AND CROYDON. 283

.J.l£icraster cor-bonis occur in the Lower Kenley Beds, but arenot found in the Upper, which appear to be characterised by theabundance of three of the best-known of Chalk species, Micrastel'cor-anquinum, Ananchytes ovatus, and Spondylus spinosus,

In his paper "On some Sections of Chalk between Croydonand Oxtead," Mr. Evans fully describes this and other sectionsexposed by the work for the formation of the railway; and thefollowing list of species from the Upper Kenley Beds of thislocality is given :-

PROTOZOA-

Cephalites campanulatus, Smith.Brachiolites convolutus, Smith.

ECHINODERMATA-

Ananchytes ovatus, Leske.Micraster eor-snguinum, Guielin.Cidaris vesiculosa, Goldf,

POLYZOA-

Desmeopora semicylindrica, Rasm,Flustra.Hornera or Homreosolen.

BRACHIOPODA­

Terebratula cemea, Sow.'J semiglobosa, Sow.

Rhynchonella Iimbata, Boblo,.. Mantelliana, Sow.

Crania Ignabergensis, Reb.LAMELLIBRANCHIATA­

Pecten qninquecostatua, Sow.Spondylus spinosus, Sow.

PISCES­

Lamna,

The summit of the Down was then crossed, and following apretty country lane the party struck the London and Brightonroad at the picturesque grove called" Purley Oaks," near to whichis the Chalk quarry in which was found a granite boulder, possiblydeposited on the bed of the old Chalk sea by an iceberg from theice-capped lands of the Cretaceous Epoch.

A rapid walk of a mile brought the Members to the outskirts ofCroydon, where the Cretaceous rocks give place to the Tertiariesof the London Basin, the southern edge of which is here found.Near to the conspicuous tower of the Croydon Waterworks, alarge excavation affords a good exposure of the junction of theSecondaries and Tertiaries, the Chalk with the overlying ThanetSands being well exposed. This was the last section visited j andthe party subsequently took train to London,