:VA'2 ROY L. MOODIE 



threads occur in tlic substance of the nodule itself and the brain 

 substance is entirely free from such threads. 



T have shown in fi»;ure 2 an enlarf>;(Mnent of 70 diameteis of a 

 portion of the meningeal space. The dark l)and at the bottom of 

 the figure is the substance of the nodule, thi-ough which the 

 plane of section is indicated in figure 1 by the heavy transverse 

 line cutting the optic lobes and the cerebellar lobes. The hght 

 area in the substance of the nodule is calcite, usually entirely 

 crystalline; the dark areas represent the phosphate of calcium and 

 are nearly opaque. On this darker area reposes the meningeal 

 space filled with threads of phosphate and calcite crystals. In 

 the upper right hand corner is a portion of the left cerebellar lobe, 

 which in the photomicrograph appears structureless, but under 

 the microscope and better under the polariscope the substance of 

 the brain is seen to be converted into incomplete crystals of cal- 

 cium carbonate (calcite) and calcium phosphate. The polari- 

 scope shows this substance in a lighter blue than the well-formed 

 calcite crystals in the meningeal space. The transverse striae 

 seen in these latter calcite crystals in the photomicrograph are 

 the orthorhombic cleavage planes of the crystals. 



It is suggested elsewhere (4) that the brain substance may 

 have been converted into palmitate or cholesteryl stearate, which 

 enabled it to retain its form until more adequate fossilization 

 could set in. In the present instance, if this were true, it would 

 also explain the preservation of the meningeal spaces which were 

 filled with a calcium magma before true fossilization set in. 



There are no traces whatever of either cartilage or bone. The 

 brain case and skull have been completely transformed into cal- 

 cium phosphate. If the phosphatic portion represents the brain 

 case, and I have every reason to believe it does, then we have 

 the interesting addition to our knowledge of Paleoneurologj^ 

 and one which justifies the publication of this paper; that is, 

 Carboniferous ganoid fishes of the paleoniscid type had a wide 

 meningeal space as do most modern fishes. This meningeal 

 space is filled with calcite crystals, separated b}- threads of phos- 

 phate giving the substance a vesicular appearance to the naked 

 eye or under low magnification. 



