of the Valley of the Thames. 165 



within the distance of a few feet, although the general character 

 is the same ; in some places the sands and clay pass into each 

 other, but they are more usually distinct. In the latter section, 

 the upper layer of brick earth in apposition with the gravel is 

 regular and horizontal, but in the former the same part is hol- 

 lowed into basins, from which fissures extend downwards, both 

 filled by the sand from above ; the usual width of the basins is 

 from two to five feet, and their depth from one to four feet, 

 whilst the fissures vary from one to five feet in length, and mea- 

 sure several inches at their widest part. I have not been able to 

 ascertain the thickness of these deposits, as the cutting is seldom 

 made lower than eighteen or twenty feet, below which the brick 

 earth is either of an inferior quality or altogether absent ; but in 

 a well lately dug in the neighbourhood, sand and gravel with 

 irregular layers of clay were met with to a depth of fifty feet. 

 Throughout the valley of the Thames bones of mammalia and 

 shells are generally found, but at no place so abundantly as at 

 Ilford. The two genera of shells, of which hundreds may often 

 be obtained at one visit, are Helix and Cyrena, but Unio and 

 Planorbis are not uncommon, and Ancylus, Succinea, Valvata, 

 Limnteus, Cyclas and Paludina have been discovered. The Helix 

 cannot be distinguished from the existing H. nemoralis, and in 

 many specimens the colouring matter is preserved : the Cyrena is 

 stated to be identical with one now living in the Nile : of the 

 other genera it is almost impossible to determine the species, 

 owing to their imperfect condition ; they are chiefly seen in the 

 layers of sand upon which the brick earth reposes, and beneath 

 the bones, but are sometimes intermixed with them, and have 

 been found even within their cavities ; they appear to be partial 

 in their distribution, and are not met with in the former cutting. 

 The bones occur both in the clays and sands, but their most 

 common position is the point of union of the two, or the upper 

 layers of sand : those from clay are in excellent preservation, but 

 all from the sand fragile and difficult to remove entire ; they ap- 

 pear to have undergone no other change than a slight impreg- 

 nation with iron and the loss of their animal matter, and for 

 their restoration I have found gelatine answer admirably. I have 

 obtained very perfect remains of the following animals : Ursus, 

 Elephas primigenius, Rhinoceros leptorhinus, Equus, Bos primi- 

 genius, Bison prisons, Cervus Elaphus, Castor europaus, Mega- 

 ceros hibernicus, Sheep, Pig, and a bird of flight of the size of a 

 crow. Of these, the remains of the Mammoth, Ox and Rhino- 

 ceros are most common, the Aurochs, Horse and Stag less so, and 

 the rest comparatively rare. They bear no marks of attrition, 

 and are always placed horizontally, and in most cases the skele- 

 tons appear nearly entire ; a perfect Elephant was gradually dis- 

 covered by the labourers a few months back, but from the greater 



