lii PROCEEDINGS, 



Epiaster gibbus, Galerites albogalerus, Micraster coranguinum, 

 M. coi'testudinarium, Oriaster sp. 



Annelida. — Sei'pula plana, S. proteus '? 



Polyzoa. — Alecto (Stomatopora) sp., Bicavia dilatata, Crisina 

 subgracilis, Diastopora sp., Domopora clarula, Entalophora 

 clavata? (echinata), E. obliqua (Clausa heteropora), E. raripora 

 (virgula), Eschara sp., Flustrellaria (Onychosella) granulosa, 

 Hippotlioa sp., Homoeosolen ramulosus, Membranipora sp., 

 Proboscina ramosa, Spai'sicava carentina, Truncatula alternata, 

 Vincularia sp. 



Brachiopoda. — Crania egnabergensis, Kingena lima, Mega- 

 tliyris (Argiope) niegatrema, Plicatula sigillina, Ehynchonella 

 plicatilis?, R. reedensis ?, Terebratula semiglobosa, Terebratulina 

 striata, Thecidium Wetherelli. 



La)nellihrancMata.—lnoceYa,ViXViS involutus, Ostrea vesicularis, 

 Pecten sp., Spondylus latus. 



It will be seen from the number of genera of which species 

 have been found which could not be determined, owing to the 

 imperfect state of the specimens, that further research might 

 result in a considerable addition to the number of known species. 



From this pit the members of the two Societies made their 

 way to Long Valley Wood, Croxley G-reen, some by train to 

 Rickmansworth and others cycling. The gravel-pits here were 

 visited in the previous year, and the accoimt of the sections given 

 in the report of that visit need not be repeated. The point of 

 most interest was the method of preservation of the mass of 

 Reading Beds there referred to. It had been preserved intact for 

 the present visit so far as possible, but the large Sarsen-stones 

 which were on the top had fallen down, and one of them had been 

 removed to the County Museum, where it now stands on the 

 right-hand side of the entrance ; the clay above the sand, also, 

 had shifted from the horizontal position in which it was first 

 seen. One of the Sarseus is represented on Plate XI. It is 

 about 5 feet long, and 2 ft. 6 ins. wide. The mass when first 

 seen was about 6 feet in height and 10 in width, and the gravel 

 was distinctly arched above it. The sand was stated by the 

 foreman of the gravel-pits to go down at least 6 feet below the 

 present level of the surface, which is here close to the Chalk. 

 This seemed to indicate a " pipe " in the Chalk. The Sarsens 

 were found to be soft in places ; one was sharply split across, 

 another was deeply mamillated. 



A visit by the writer this summer (1908) showed that 

 " piping " was the cause of the preservation of this patch of 

 Reading Beds, and of the curvature of the stratum of gravel 

 above it. It had been in a " pipe," but the chalk around it has 

 been dissolved by carbonated water, which has not affected the 

 Tertiary material. The gravel above it has therefore remained 

 in the position in which it was deposited, but has sunk around 

 it where resting on the Chalk, thus assuming an arched form. 

 This explanation implies an enormous lapse of time since the 



