316 Mr Horner on the occurrence of the MegaUchthys 



containing the same class of plants. * It is clear, therefore, 

 that the mere existence of terrestrial plants does not prove a la- 

 custrine deposit. 



3d/^, As to the remains of fish. These are the Megalichthys, 

 Pygopterus, Amblypterus, and Eurynolus, and are supposed to 

 have approached the cestracion of modern times. 



Dr Hibbert considers the Megalichthys as a fresh-water fish, 

 in one part of his memoir, for, in describing the circumstances 

 under which he conceives the coal deposits of Scotland to have 

 taken place, he says, *' During such a condition of the globe, 

 the calcareous deposit of Burdiehouse was formed, new races 

 of fish inhabiting y/-^^/i waters were created, and among them 

 the Megalichthys.'''' — P. 258. And, in another place, he says, 

 " As the remains of the Megalichthys are found in bituminous 

 shale, and even in coal itself, it is evident that the animal must 

 have frequented shallows and wet marshes." — P. 262. He points 

 out the analogy, observed by M. Agassiz, between the Mega- 

 lichthys and the recent Lepidosteus ; speaks (p. 207) of the Le- 

 pidosteus Spatula as being " a living type of the Megalichthys; 

 and states (p. 213) that the Lepidosteus dwells among the lakes 

 and rivers of the most thermal regions of America. In speak- 

 ing of the coprolites, however, he makes use of some expres- 

 sions which would seem to indicate a different view, viz. that 

 this great fish must only have been an occasional visiter of fresh 

 water. He says, " In proportion as coprolites increase in size, 

 we find that they contain the scales of fish, shewing that the 

 larger fish,^to which these foecal remains are referred, must have 

 frequented the ancient river or lake, indicated by the limestone 

 of Burdiehouse, in quest of their prey.'"' Now, this is obvious- 

 ly quite inconsistent with the idea of a " pure lacustrine forma- 

 tion,*" for when he speaks of large fish frequenting the ancient 

 river or lake in quest of their prey, he obviously means that 

 they were not regular inhabitants of the river or lake; and as 

 we must presume that they came from the sea, and must have 

 swam into the lake, it must therefore have communicated with 

 the sea. But there is a passage in Dr Hibbert's memoir which 



• For an account of Professor Jameson's discoveries in this locality, see 

 Proceedings of Wernerian Natural History Society, in Edinburgh Philoso- 

 phical Journal, January 1836. 



