XVIU 



Page 



The Seal's iris 722 



Skull and horns of Cobus craxcshayi 727 



Capra caucasica '^^ 



Fig. 1 a. Petromyzon Jluviatilis, 25-5 centim. total length, showing 

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

 from beneath. Fig. 2 a. P. Jluviatilis, 2.3-5 centim., showing 

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



dissected from beneath 731 



Fi"-. 3. Myxine glutinosa, dissection from beneath of a specimen 



possessed of a supernumerary gUl on the left side 731 



