Variations in Spinal Nerves of Hyla aiirca. 275 



3. While XTI. decreases, IX. increases. Nerve XII., thick- 

 ness 2, is only found with nerve IX., thickness 9, while nerve 

 XII., thickness 1, is also found with nerve IX., thickness 11. 



I. While XII. decreases, VIII. decreases also. Nerve XII., 

 thickness 2, is found only with nerve VIII., thickness 5, while 

 nerve XII., thickness 1, is found also with nerve VIII., 

 thickness 3. 



5. While XII. decreases, IV. increases. Nerve XII., thick- 

 ness 2 is only found with nerve IV., thickness 3 ; while nerve 

 XII., thickness 1 is also found with nerve IV., thickness 4. 



6. While XII. decreases, III. decreases also. Nerve XII. 

 only occurs with the central thicknesses of the series for nerve 

 III.: but these appear to show that nerve III. decreases with 

 nerve XII. Thus : Nerve XII., thickness 2 is only found with 

 III., thickness 12, while thickness 1 of nerve XII. is also found 

 with nerve III., thicknesses 10 and 11. 



7. This table shows no regularity whatever. 



8. While XL diminishes, so does X. In the higher thick- 

 nesses of nerve X., there are some irregularities, but from 

 thickness 10 downwards, nerve XI. seems to decrease in 

 thickness as nerve X. also diminishes. The frequency of 

 nerve X., thickness 10, diminishes almost regularly with the 

 decreasing thickness of nerve XL, and was never noted in 

 combination with thickness 1 of nerve XL The frequency of 

 nerve X., thickness 9, decreases with a falling thickness of 

 nerve XL, reaching a minimum with nerve XL, thickness 2. 

 The frequency of nerve X., thickness 8, increases and then 

 decreases with decreasing thickness of nerve XL, and in the 

 smaller thicknesses of nerve X., the frequency increases with 

 a diminishing thickness of nerve XL, as would be expected. 



9. This table shows a somewhat irregular combination. 

 While nerve IX. increases, nerve XL first increases and then 

 diminishes. The frequency of nerve IX., thickness 7, increases 

 with increasing thickness of nerve XL, while nerve IX., thick- 

 ness 8, and nerve IX., thickness 9, are very irregular. 



10. If we overlook irregularities in the smallest and higher 

 thicknesses of nerve VIIL, we find that as nerve XL diminishes, 

 nerve VIIL increases. The frequency of nerve VIIL, thick- 

 nesses 3 and -4 varies greatly. That of nerve VIIL, thickness 



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