362 



PALEONTOLOGY OF OHIO. 



four superior branchihyals, 6/ h", are supported by corresponding inferior 

 or haemal branchihyals, hv' , hv'\ and these in turn are articulated each 

 to its proper axialhyal, ah", ah'". The absent elements are the two axial 

 and two hsemal elements, which exist as supports of the posterior two 



Fig. 7. 



NECTUEUS MACULATUS. 



superior branchihyals, 6'", 6"", in the fishes. In the branchiferous Nec- 

 turus maculatus a considerable modification ensues. The four superior 

 branchihyals are present, but according to Fischer the first and second 

 are confluent, and are supported by confluent hsemal elements. (See fig. 

 6, b' h" and hv' bv".) A third inferior branchihyal is added. If we now 

 turn to the air-breathers, Protonopsis (fig. 7), we observe a marked pecu- 

 liarity. The third haemal branchihyal remains, while the second is con- 



