On the Tarsus and Carpus of Birds. 



149 



should have either a third bone iu the leg, which would be contrary to all 

 analogy, or a third member of the near tarsal series, which would, so to 

 speak, be out of place. 



Truly yours, 



J. WYMAN. 

 Cambridge, Dec. 20, 1871. 



I have examined with the greatest interest, this new tarsal 

 bone of the heron, and from tlie specimens kindly loaned me 

 by Prof. Wyman, have made the following drawings. The 

 figures represent different stages of the tibia, from the front, 

 with the pretibial bone at the 

 base. 



Figure 1 is magnified, the 

 natural size of the tibia beins; 

 represented by a line at its side. 

 Figures 2, 3 and 4 are natural 

 size. 



In referring to Huxle3''s fig- 

 ures of the tibia of the young 

 ostrich,* and of the young 

 fowl,f I find the so-called proc- 

 ess of the astragalus, on the 

 outer side of the tibia, occu- 

 pying the same region as that of the pretibial bone of 

 the heron, and this leads me to believe that this so-called 

 process of the astragalus in the birds just mentioned, is 

 identical with the pretibial bone of Wyman. % 



* Quarterly Jour. Geological Soc, Vol. XXVI, part I, p. 30. 



t Anat. Vert. Animals, Huxley, p. 29G. 

 X Since writing tlie above, I liave received from Prof. Wyman tlie distal portion of a 

 tibia from a still older specimen of the blue heron. Accompanying the specimen he 

 writes, " This bird had not left the nest, notwithstanding its large size. You will see 

 the pretibial piece coossified with the astragalus and calcaneum, though neither of them 

 is consolidated with the tibia. There is nothing now in this specimen to show that the 

 ascending portion was ever free from the astragalus." 



We herewith give a figure of it iu section, natural size (Fig. 5); see next page. This 

 removes all doubt as to the relation of the pretibial bone, with the so-called process 

 of the young fowl and young ostrich alluded to above, and leads to the belief that 

 the tendon-like bridge, spanning the groove in front, originates from this piece, as 

 stated by Parker. He also speaks of this process in Balieniceps rex as forming '• the 

 seat of the ossification whicli makes the large wide oblique tendou-like bridge. Prof. 

 Wyman infoi-ms me that the two are not identical." 



Fig. 1. Fig. 2. Fig. 3. Fig. 4. 

 The stjde shaped bone at lower end of 

 tibia represents intermedium, or pre- 

 tibial bone of Wyman. 



