140 Mr BRODIE, on LAND AND FRESHWATER SHELLS, &c. 



It is well known, that there are three kinds of diluvial drift in the country round Cambridge. 



(I.) The great hrown clat/ forming the table-land between Canabridgeshire and Bedfordshire — extending 

 in patches, sometimes of verj- great extent, through Norfolk, Suffolk and Essex, &c. &c. — often containing 

 rounded masses of stone of considerable size. 



(2.) A coarse gravel generally occupying the crests of hills, e.g. Harston Hill, and the Gogmagogs. 

 Among the rolled masses in this gravel may be found specimens of most of the older formations of England. 



(3.) The fine flint-gravel of the lower lands, the well known material for the repair of the roads. It is 

 a very extensive formation, and though often indicating the irregular action of water, is generally at a nearly 

 dead level. It appears to have been formed during some long period, while the water (by the elevation of 

 the land) was slowly subsiding to what is called a lower level. This gravel is the newest formation of the 

 three; and over it comes the bog earth, the deposits from land floods, and the vegetable soil. 



Bones of the beaver (?), and certainly of the mammoth, rhinoceros &c. &c., have been found in the brown 

 clay (No 1.), but the organic remains of mammals are most abundant in the flint-gravel (No. 3.), though 

 generally in a very bad state of preservation, and much rubbed and comminuted. In a few spots, where the 

 coarser flint-gravel alternates with masses of fine siliceous sand, the bones and teeth &c. are found entire ; 

 but even then they are generally so brittle that they cannot be extracted or preserved without considerable 

 difliculty. If the above explanation be true, there can be no difficulty in understanding how remains of 

 mammals, and land or freshwater shells, may have been drifted into the flint-gravel during the period of its 

 formation : but this is a point, the discussion of which would lead rae beyond the limits of this note. 



Among the fossil remains of mammals in the flint-gravel (No. 3.), the bones of the following genera 

 deserve notice. 



(I.) Mammoth, or fossil elephant. The remains of this species are most abundant — such as molars and 

 tusks, sometimes quite entire ; fragments of the pelvis and other strong portions of the skeleton. 



(2.) Rhinoceros, also very abundant. In the Barnwell gravel I have found many molars, a humerus, 

 a femur ; and bones of the extremities, such as metatarsals and metacarpals, &c. 



(3.) Hippopotamus — one or two fragments of molar teeth, but rare. 



(4.) Equus — teeth and other bones in considerable abundance. 



(5.) Bos, very abundant — Remains, such as teeth, horns, fragments of the leg bones, jaws, portions of the 

 cr.anium, &c. &c. are scattered through the flint-gi-avel. The species, or variety, seems to have been like that 

 of Walton, and was of enormous size. A portion of a fine cranium was found by Mr Okes : a perfect ramus 

 of the lower jaw was found by Dr Clark in the gravel pits of Parker's Piece. 



(6.) Cervus — bones, &c. of several species — among them are fragments of the horns of the gigantic cervus 



(Irish Elk). ^__,^ 



/ ■J^^^^it^^^N A. SEDGWICK. 



/^ fr.' sU ■>% 'A 

 TniNiTY College, / j)9&f,<f^''^ \ 



March8,lSi4. [ iVkviO'l'C' j 



N.B. The aliove communication of Mr Brodie was unfortimately mislaid ; and, in consequence, its publication has 

 been delayed more than five years. 



