60 
But the fact that these strata at the base of the Lias are 
now generally classed with the Rheetics, and therefore inter- 
mediate between the Lias and the Trias does not weaken 
the argument in favour of a change of life at this particular 
time. For while in Germany the whole series including the 
St. Cassian group below, are of great thickness, and there- 
fore, are entitled to be ranked as a separate and independent 
formation; their representatives in England do not exceed 100 
feet, and might be fairly considered to be more truly passage 
beds though of Rheetic age. I am not aware that any ‘bone 
bed’ properly so-called, occurs in the district where the 
Rheetic and St. Cassian formations are most largely de- 
veloped. 
Whether these different bone beds indicate as some 
Palzontologists suppose, a break or change in the mineral 
and zoological conditions prevailing at the time, or whether 
they rather shew a continuity in the Geological record, thus 
forming connecting links between one great Geological 
period and another, we should in either case expect to find 
many new forms of animal life mingled with others which 
characterize the older underlying formation; while some 
would die out, and perhaps remain peculiar and distinctive, 
and a few pass upwards into the later deposits which 
succeeded in the order of time. 
4.—Bone bed’ at the base of the mountain limestone at its 
junction with the old red sandstone. 
5.—Bone bed’ at the base of the old red sandstone at its 
junction with the Ludlow rock. 
We have here then no less than five bone beds in five 
distinct Geological formations, all occurring at the close of 
one period and the commencement of another, which is so 
marked and peculiar that it seems almost impossible to doubt 
