238 Correspondence — Ghas. E. P. Brooks. 



OORRESPOnSTDENCE. 



ZONES OF THE CHALK AEEA OP NORTH-WEST MIDDLESEX 

 AND EAST BUCKS. 



Sir, — For some time up to about two years ago I was occupied, 

 when occasion permitted, in zoning the Chalk area of North- West 

 Middlesex and East Bucks. Latterly I have been too busy, and 

 I find the chance of my ever being able to take up the work again 

 very remote. I am therefore sending you a note of such results as 

 were obtained. 



The sections most carefully worked were — 



(1) About 1 mile N.W. of Denham, in the most southerly Chalk outcrop. 



(2) About 1 mile N. of Denham, just under the h5 in the 1 in. drift sheet. 



(3) Troy Mills, about 2 miles N of (2). 



(4) Harefield Cement Works Pit. 



(5) Harefield Gelatinous White Co.'s Pit. 



(6) Springwell Pit. 



(7) Pit on Golf Course at Sandy Lodge. 



Harsupites and Vintacrinus were nowhere found, in spite of careful 

 search. From Nos. 1 and 2 came several high-zonal If. cor-anguinutn, 

 and from Nos. 3, 4, and 7 low-zonal cor-anguinum. In Nos. 5 and 6, 

 both of which have a section of about 80 feet from the pit floor to the 

 top, the floor in each case being nearly at the same level above O.D., 

 both M. cor-anguinum and M. cor-testudinarium were found, as well 

 as passage forms, so that both these zones would seem to occur. 

 M. cor-testudinarium was also found in an excavation below the level 

 of the floor at Harefield. The junction of the zones can be con- 

 veniently taken at a band of comminuted mollusca and echinoids 

 which occurs in both sections. 



This band was only a few feet above the floor at Harefield, but at 

 Springwell it was about half-way up, or nearly 40 feet above the 

 floor. This gives a difference of 30 feet in a north-south distance of 

 H miles, or 20 feet to the mile. As M. cor-anguinum was found near 

 Cnorley Wood, nearly two miles north of Springwell, and the same 

 species occurs near Watford, there must be a rather sharp flexure 

 of the Chalk south of: liickmansworth, bringing up the lower zones. 



Fossils are not common, except in the lower parts of pits 5 and 6, 

 i.e. in the M. cor-testudinarium zone. Most characteristic are a 

 flat broad-based pentangular variety of Discoidea cylindrica and 

 Echinocorys vulgaris. Parasmilia centralis was not infrequent. The 

 flints are very spongiferous. Chas e> p Beooxs. 



"HOMELEIGH," 3 ROSELEIGH AVENUE, 



Highbury, N. 



OBITUAEY. 



RICHARD LYDEKKER. 



B.A. (Camb.), F.E.S., F.G.S., F.Z.S., J.P. Herts. 



Born 1849. Died April 16, 1915. 



It is with deep regret we have to record the death at Harpenden, 



in his 66th year, of our esteemed friend Richard Lydekker. He 



was for many years a fellow-worker in palaeontology with your 



Editor, in the British Museum (Natural History), where by his 



