Address to the Lincolnshire Naturalists’ Union. 267 
killed by the salinity of the waters of the inland lake? or, 
perhaps, after life had developed through the change of water, 
the land temporarily rose again, or became stationary for a time, 
and, the salinity returning, the fishes, no longer able to sustain 
life, perished, and their remains sank, in a layer, on the sea floor. 
There is another fact of interest connected with the Rheetics, 
which must not be omitted before we leave them, and that is, 
that the earliest known British mammal, the Microlestes, a small 
insect eating animal, is found within its strata. The Rheetic 
beds contain also remains of the huge Saurians which are so 
characteristic of the Lias and higher formations; and we are 
indebted to Mr. Montagu Browne, of the Leicester Museum, for an 
account of several new species, which he recorded at the recent 
meeting of the British Association at Oxford, as well as on two 
former occasions. Remains of Saurian life occur also in the 
Rheetic strata at Lea, near Gainsborough. 
AND now we pass on to the Lias, the lower beds of the 
Jurassic system, in which the ironstone bands of Frodingham and 
Appleby are found, and change to a deep sea; the remains of 
which, beginning a little way to the east of Gainsborough, 
extend right across to Lincoln, and form the material of the Cliff 
there, to within 20 feet of its summit. 
This sea is one of great interest, it covered a great part of 
England with a portion of Ireland, and ran up far north into 
Scotland, having rivers to feed it from the adjoining lands 
around; while, to the south, it extended down towards the 
tropics. Its depth was considerable, and, as its strata show, its 
waters teemed with life. Fish, reptiles, molluscs of many kinds, . 
echinoderms, insects, wood and corals, are met with in its layers. 
‘The insects,—which, according to Westwood, belong to no less 
than 24 families, and comprise both wood-eating and herb- 
devouring beetles, grass-hoppers, dragon-flies, and may-flies,— 
together with the wood, were, doubtless, brought down by the 
‘rivers which flowed into the sea; while the corals owe their 
presence to the extension of its waters southwards, enabling the 
products of warmer climes to push up towards the north. 
