FOSSIL FISH BRAIN 



331 



it was well that staining was not attempted, since there are no 

 evidences whate^'er of organic structure; only the outer form of 

 the brain, nerves and semicircular canals are preserved. 



In attempting to solve the problem presented by the preserva- 

 tion of these little fish brains I was at a loss to explain the fate 

 of the meningeal space which in most of the recent fishes is quite 



Fig. 2 Photomicrograph of a section through a brain-containing nodule from 

 the Coal Measures of Kansas. X 70. There are three important areas in this 

 untouched photograph: 1) A dark area running entirely across the picture at the 

 bottom, extending about one-third of the distance up the right side, and running 

 obliquely downwards to the left, representing the phosphate or substance of 

 the nodule which has replaced the brain case. The upper surface of this substance 

 then represents the floor of the brain case. 2) A lighter area composed of 

 rounded irregular spaces representing the meningeal space which has been filled 

 with calcite. 3) The substance of the brain itself, or at least a portion of the 

 left cerebellar lobe, showing its structureless nature. This area is seen in the 

 triangular portion cut off by a dark band in the upper right hand corner of the 

 figure. The most important and only new thing established by this figure is the 

 extent of the perineural space, which is seen to be quite large and is comparable 

 to the meningeal spaces of modern fishes. 



extensive. The meningeal spaces in the present fish brain are 

 filled with masses of calcite crystals which are separated by 

 threads of calcium phosphate. The phosphatic threads may be 

 the representatives of blood vessels but I doubt it since the same 



