236 



Scientific Geology. 



Ichthyolitcs. 



The remains of fish have been found on bituminous shale and bit- 

 uminous marlite, in Middletown, Ct. at Sunderland, Mass. and also in 

 West Springfield and Deerfield. Sunderland, however, is the only- 

 spot where they can now be procured. The shale there forms the 

 bank of the river several feet high : but the ichthyolites are most 

 abundant in the lower part of the bed, which corresponds nearly with 

 low water mark. I have dug out hundreds of specimens at this 

 spot ; though perfect ones are very rare to be obtained. On one 

 layer of the rock, fifteen inches by three feet, seven distinct impres- 

 sions were visible. Indeed, I have not unfrequently met with one 

 fish lying across another, without the intervention of a layer of 

 shale : and from these specimens, I can easily conceive how the mis- 

 take should have been made, that among the Monte Bolca ichthyo- 

 lites, one fish was found in the act of swallowing another ! 



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, how- 

 ever, satin spar forms a thin layer over the carbonaceous matter, and 

 being of a light gray color, it gives to the specimens an aspect ex- 

 tremely like that of a fish just taken from the water. 



We sometimes find the specimens a good deal mutilated ; so much 

 so, indeed, that the form of the fish is entirely lost ; and the scales 

 and fins are scattered about promiscuously : and this too in the vicin- 

 ity of other specimens that are entire. Hence we cannot impute 

 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 envel- 

 oped 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 animal : 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 Mansfeld, in Germany, has been already noticed. 

 Probably all of them belong to the genus Palaeothrissum. I am 

 inclined to believe that I have found four species. Plate XIV. Figs. 

 45 and 48, are probably the same species ; the outlines of the latter 

 being sketched, merely because they are more distinct than those of 

 fig. 45. Forty nine fiftieths of the specimens at Sunderland belong 



