376 Correspondence. 



from Leicester to Chelmsford, and from Buckingham to the East 

 Coast, I never until lately succeeded in obtaining a reliable shell. 

 I recently, however, found two perfect specimens of Ostrea edulis in 

 the Middle Glacial gravel, above the Brick-clay, in the disused brick- 

 field at Stevenage. Any one having local opportunity would do 

 good service by hunting this locality before the field is levelled and 

 closed up, which is now being done. 



As 0. edulis is not an arctic shell, and occurs as far south as 

 Gibraltar, its presence, as far as it goes, accords with the other 

 characters of this formation in shewing that the Middle Glacial was 

 not an arctic deposit. 



Yours faithfully, 



Searles V. Wood, Jun. 



Brentwood, Essex, June 7, 1867. 



P.S. — The obscure specimens of shell obtained from Saxlingham, 

 Mr. Taylor will, I think, find belong, not to the Middle Glacial, but 

 to the Chillesford beds (i.e. his Upper Crag), which are present 

 there in a feeble form resting on the Chalk. Those obtained by him 

 from Sprowston I presume are from the Middle Glacial sands, as 

 the Upper Drift does not occur, to the best of my knowledge, at, or 

 within, some four or five miles of that place. Perhaps, however, 

 he may refer to some small outlier that Mr. Harmer and I have 

 missed, or, possibly "Upper" may be a misprint in his letter for 

 "Lower." 



ON THE NATURE OF EOZOON. 

 To the Editor of the Geological Magazine. 



Sir, — Having been engaged for some time on a paper on classifi- 

 cation, with especial reference to the Mollusca, I had already in the 

 introductory part of it written the greater part of what follows when 

 I read in the Geological Magazine an abstract of a memoir by Dr. 

 Dawson on Eozoon. As it may be some time before my paper just 

 referred to is ready for publication, I send you this part of it at once. 



It will doubtless be some time before the true relations of Eozoon 

 Canadense are finally settled. But before Mr. Hancock's paper on 

 "Boring Sponges"^ appeared, I was decidedly of opinion that the 

 Eozoon had nearer relations with the Sponges than with the Fora- 

 minifera. That paper has quite confirmed me in this view ; for Mr. 

 Hancock shows the great similarity which exists between the dis- 

 position of the cells and sarcode in Cliona and Orhitoides. The latter 

 genus was chosen by Dr. Carpenter for comparison with Eozoon to 

 show the foraminiferal nature of the latter, and Mr. Hancock might 

 fairly have carried on his comparison to Eozoon. Any one who 

 compares the figures accompanjdng Dr. Carpenter's memoir on 

 Eozoon in the Quarterly Journal of the Geological Society with Mr. 

 Hancock's diagram of Cliona, will not fail to be struck by the simi- 

 larity. Doubtless the Eozoon is allied to Ehizopoda as well as to the 

 ^ Ann. and Mag. Nat. Hist., Srd ser. yoI. xix. p. 229. 



