1854.] BLANFORD — SECTION AT WEST INDIA DOCKS. 433 



they have small unconvoluted brains, they are unguiculate and 

 claviculate ; some are fitted for flight (VespertilionidcB) , some for 

 swiftly burrowing in the earth {TalpidcB), some for swimming and 

 diving (Soricidcs), others for rapid course over the dry land {Ma- 

 croscelidce) . 



All that can be legitimately inferred as to the grade of mammalian 

 structure now brought to light from the oldest of the Wealden epochs 

 is that it displays the mammalian modification which we know to be 

 best adapted to profit by a co-existence with the insect population of 

 the same period. 



2. On a Section lately exposed in some Excavations at the 

 West India Docks. By W. T. Blanford, Esq. 



[Communicated by the President.] 



An excavation lately made to join two portions of the West India 

 Docks has exposed a section of the deposits in the valley of the 

 Thames to a depth of above 30 feet, showing beds of peat vpith stems 

 of trees, and, below these, gravels containing organic remains. The 

 thickness of the different beds varies considerably, but their general 

 succession and their measurement where best exposed are shown by 

 the accompanying diagram, p. 434. 



The two beds, c & d, vary in character and thickness ; stems of 

 trees, most of which lie horizontally, though some of the smaller ones 

 are vertical, are scattered throughout the peat ; and this deposit is in- 

 terspersed with specks of blue phosphate of iron. Throughout the 

 clay, c, are sparingly scattered the following species of freshwater 

 shells : — 



Bithinia tentaculata. Limnaeus pereger. 



Limnseus palustris. Ancylus fluviatilis. 



At the bottom of the bed of peat at one place a considerable num- 

 ber of land and freshwater shells of the following species occur (the 

 bivalves having both valves together) : — 



Helix nemoralis. Bithinia tentaculata. 



H. rotundata. Ancylus fluviatilis. 



Clausilia laminata. Pisidium amnicum. 



Succinea putris. Unio. 

 Valvata piscinalis. 



This bed, d, rests on the very uneven surface of the underlying 

 clays, sands, and gravels (e,f, g), which are much false-bedded, and 

 in some places evidently deposited by currents of considerable strength , 

 beds of sand and small rolled pebbles, dipping at a considerable angle, 

 lie between other beds which are horizontal, though thinning out at 

 short distances. Towards the bottom these are exclusively of pebbles, 

 much larger than those in the upper part, and mainly composed of 

 chalk- flints, some of which are very much rolled, others very little ; 

 many broken, and with the edges but little rolled. Pebbles of dif- 

 ferent kinds of sandstone and of vein-quartz also occur. 



