R. M. Brydone — Further Notes on the Trimmingham Chalk. 127 



ohalk cliff running along the bed of the North Sea, and such a cliff 

 would be a possible source, and the only one that can be suggested, 

 for the erratics between Trimmingham and Weybourne. Some cliff 

 the source must have been, for ice with all its powers can neither 

 shovel up nor suck up large masses of chalk out of a horizontal 

 surface. This hypothetical buried cliff would probably be running 

 more or less north and south, and would therefore be nearer to the 

 present coastline at Overstrand than further north, and the 

 difference in distance travelled would account for the enormous 

 difference between the condition of the Overstrand erratics, which 

 have suffered somewhat, but not much, from pressure, and those west 

 of Cromer, which have been crushed until they are barely coherent, 

 and crumble most rapidly on exposure. The suggested Pliocene 

 chalk cliffs would also afford a source for the enormous supply of 

 carbonate of lime which must have been required for the building up 

 of the vast masses of shells of which the lower Crag beds are composed. 

 [After this paper had taken more or less its present shape, 

 Professor Bonney and Mr. Hill published in the Geological 

 Magazine for September, 1905, a paper dealing somewhat sketchily 

 with the purely stratigraphical aspect of the Trimmingham Chalk on 

 apparently very incomplete data. This paper has been effectively 

 criticized by Mr. B. B. Woodward in the October number of the same 

 Magazine, pp. 478 and 479, and by Sir Henry Howorth in the 

 November number, and I have nothing to add to the criticisms 

 made by these gentlemen, to whom I am much indebted for their 

 intervention. We have, however, to thank Professor Bonney and 

 Mr. Hill for a record of chalk at the base of the cliff under 

 Trimmingham itself, where I have long expected it, but never had 

 the good fortune to see it.] 



Paleontology. 



A. Chalk of Trimmingham. 



The greater number of the additions and corrections to the list 

 given in my previous pamphlet have been incorporated in the list 

 to be found in the recent Survey Memoir above referred to, but for 

 convenience a complete list of all corrections and additions is 

 given here :-r- 



Sponoida. 

 Add Porosphara glohularis, Phill. ; Ventriculites deeurrens, T. Smith ; V. impressus, 



T. Smith ; V. quincuncialis, T. Smith ; V. radiatus, T. Smith. 

 Omit P. Woodwardi — the light recently thrown by Dr. Hinde on the species which 

 has so long borne this name makes me doubtful if I can prove its occurrence. 



ACTINOZOA. 



Add Diblasus Grevensis, Lonsd. 



Omit Calamophyllia faxeensis — the specimen which distantly suggested this species to 



Professor Deecke has proved to be a fish -spine {Coslorhynclms cretaceus) ; 



OnchotrocJius serpentimis — this appears to have been based on specimens of 



a very slender Porina. 



Echinodermata. 

 Add Epiaster gihhus, Lam. ; Micraster eor-anguinum, Klein. One specimen of the 



former and two of the latter are in the collection of Mr. Savin. Echinoconiis 



Orhignyamis, Ag. (the buu-shaped Echinoconus of my previous pamphlet 



according to Mr. Sherborn). 



