Complete Fibula in existing Birds. 



365 



formed throughout in true bone, tlie fibula in Plotus anhinga 

 is extremely slender for its lower fourth. 



In an article entitled '' Remarks upon the Osteology of 

 PhalacYocorax bici'istatus," I have already invited attention 



Fi.A 



Fb. 



-Tb. 



Fig 2. 



rig 1 



Fig. 1. Right tibio-tarsus and fibula of Plotus anhinga, seen upon their 

 anterior aspect. Drawn of the natural size from the specimen 

 by the author. (Coll. U.S. Nat. Museum, No. 18259.) 



Fig. 2. The corresponding bones as found in a skeleton of Sula piscafor ; 

 same aspect, and also drawn of the natural size by the author 

 from the specimen in Coll. U.S. Nat. Museum, No. 18739. The 

 fibvda in both figures is marked Fb., and the tibio-tarsus Tb. 



to the condition of the leg-bone we now have under con- 

 sideration, in the following words : — " The fibula is carried 

 unusually far down the side of its companion bone to within 



