DESIDERATA, ETC. 
XXV11 
should be observed, in relation to the same circumstances in 
the dykes and mineral veins of the vicinity; with a view to 
ascertain whether any and what dependence there may be be¬ 
tween these phenomena'*. 
7. That the quantity of Mud and Silt contained in the water 
of the principal rivers of Great Britain should be ascertained, 
distinguishing, as far as may be possible, the comparative quan¬ 
tity of sediment from the water at different depths, in different 
parts of the current, and at different distances from the mouth 
of the river; distinguishing also any differences in the quality 
of the sediment, and estimating it at different periods of the 
year; and that the sum of 20/. be placed at the disposal of the 
Rev. J. Yates and Mr. G. Rennie, for the purpose of these ex¬ 
periments. 
8. That with a view to the improvement of our knowledge of 
the Fossil Ichthyology of the British Islands, a sum not ex¬ 
ceeding 105/. be paid to Dr. Buckland, Prof. Sedgwick, and Mr. 
Murchison, to be applied for the purpose of assisting M. Agassiz 
in carrying on his Ichthyological work. 
8 a. That a further sum of 105/. be applied to the same pur¬ 
pose. 
9. That a Catalogue be formed of all known Basaltic Dykes 
in the United Kingdom, with an account of the direction of 
each in regard to the meridian, the distance of which it has been 
traced, and the rocks which it passes through. 
10. That a list be collected of all places in which Shells of 
existing species have been found on dry land, with the heights 
of such places above the mean tide levels, and their distance 
from the coast, specifying the names of the several shells, and 
the area over which they extend. 
10 a. That evidence be collected as to the direction and pro¬ 
bable sources from which drifted blocks and pebbles referrible 
to rocks not existing in the neighbourhood, where they now 
occur as insulated blocks or in beds of superficial gravel, may 
have been derived. 10 h. That evidence be collected as to the 
form and direction of hills or ridges of superficial gravel, and 
the sources whence the materials of such gravel-hills may have 
been transported to their present place. 
10 c. That observations be made on the direction and depth 
of grooves and furrows, such as are often found on the faces of 
hard rocks and beneath superficial deposits of drifted clay and 
gravel not referrible to the action of any existing currents. 
* Professor Phillips has stated (see Reports, vol. iii. p. 654,) the results of his 
examination on this subject in certain parts of the North of England, and re¬ 
quests to be favoured with communications relating thereto. 
