GEOLOGICAL SOCIETY. 



93 



another, without the intervention of a layer of shale, 

 and from these specimens, I can easily conceive how 

 the mistake should have been made, that among the 

 Monte Bolca ichthyolites, one fish was found in the 

 act of swallowing the other. 



" A thin layer of carbonaceous matter usually marks 

 out the spot where the fish lay, except the head, whose 

 outlines are rendered visible only by irregular ridges 

 and furrows. In some cases, however, satin spar 

 forms a thin layer over the carbonaceous matter, and 

 being of a bright gray color, it gives to the specimens 

 an aspect extremely like that of fish just taken out of 

 the water. 



u We sometimes find the specimens a good deal 

 mutilated ; so much so indeed, that the form of the 

 fish is entirely lost, and the tail and fins are scattered 

 about promiscuously ; and this too in the vicinity of 

 other specimens that are entire. Hence we cannot im- 

 pute this mutilation, as is usually done, to a disturbing 

 force acting on the rock at the time in which the fish 

 was enveloped, or afterwards. But if we suppose that 

 the fish, as they died, were gradually enveloped by 

 mud, it is easy to conceive how some of them might 

 have putrified and fallen to pieces, before they were 

 buried deep enough to be preserved ; or it might be, 

 that most of the fish was devoured by some other ani- 

 mal : and in either of these ways, we might expect to 

 find only scattered relics enveloped in the rock. The 

 great resemblance of these ichthyolites to those found 

 on the bituminous slate of Mansfield, in Germany, has 



