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The Seal's iris 722 



Skull and horns of Cobiis craicshayi 727 



Capra caucasica 730 



Fig. 1 a. Petromyzon fluviatilis, 25"5 centim. total length, showing 

 vestigial first gill on left side. Fig. 1 b. The same, dissected 

 from beneath. Fig. '2 a. P. Jluviatilis, 23'o centim., showing 

 absence externally of fii-st gill on right side. Fig. 2 h. The same, 



dissected from beneath 7.31 



Fig. 3. Myxine ylutinosa, dissection from beneath of a specimen 



possessed of a supernumerary gill on the left side 731 



