198 



ON SOME TRAILS AND HOLES FOUNB IN ROCKS 



omphaloides, embedded in the body of the fossil two-tenths of 

 an inch in depth. It is possible in both these instances that 

 when the fossil plants were in a soft pulpy state, and the shells 

 were attached to them, superincumbent pressure might have 

 squeezed the shells into the substance of the plants. But in 

 both cases we should expect to discover some portion of the 

 coaly matter squeezed in as well. This I do not find. 



Now is it probable that some of the shells described as 

 belonging to the genus spirorbis were inhabited by boring 

 molluscs or worms ? In the bed of shells before alluded to 

 as occurring above the Arley Mine at Wigan, and generally 

 termed large unios, (?) are many specimens having holes bored 

 in them, — thus plainly shewing that boring molluscs or worms 

 did then exist. In this bed the spirorbis abounds as well as 

 the so-called unio. So after all the disputes as to the nature 

 of the microconchus, it may possibly be that in some species 

 at least its inhabitant was a mollusc allied to teredo, and not 

 an annelid, as has generally been supposed. 



In former communications* published by the author he has 

 brought forward both the fossil fishes and the fossil plants, to 

 shew that the waters of the carboniferous epoch were nearly 

 if not altogether of a marine character. The facts described 

 in this paper of the meandering trails of molluscs, the bur- 

 rowings of worms, the occurrence of shells pierced with 

 boring animals, and the parasitical annelids found attached to 

 plants and shells, all tend to the same conclusion. But 

 beyond all other proof of the marine character of the water 

 of the carboniferous age, is the water itself now found mixed 

 with the coal, and where it has remained for countless ages 

 pent up and hermetically sealed. In deep mines, where the 

 seams of coal have not been subjected to the percolation of 

 surface water, but protected by compact beds of indurated 

 clay, the water is nearly always saline, and contains iodine 



* Transactions of the Manchester Geological Society, vol. i. p. 173 ; Memoirs 

 of this Society, vol. viii. (new series) pp. 24 — 



