202 MR. W. K. PARKER ON THE OSTEOLOGY 



depth of the entire keel in both specimens being the same, viz. 10^ lines. We shall 

 see, when we turn to the Tinamus, how the thinness of the great pectoral, and over- 

 thickness of the middle muscle, bear upon the affinities of these birds. It is right to 

 state, however, that the sternum of this Syrrhaptes is somewhat diseased at the keel-edge 

 (PI. XLI. fig. 4), and perhaps more room ought to be allowed for the great pectoral. 



In the various Fowls and in the Syrrhaptes, the air only enters the body of the 

 sternum at its anterior end, above ; in Pigeons the mesial groove is riddled with holes. 

 The hyosternal processes (PI. XXXVIII. hs.) are not long and forthstanding as in the 

 Fowl (PI. XLI. figs. 9 & 10, hs.) and the Grouse, not short and retral as in the Pigeon 

 and Talegalla ; they are small, triangular, and upright, as in the Plovers. In the Syr- 

 rhaptes, as in the Pluvialines and many other birds, the lower episternal piece (Pi. XL. 

 fig. 4, ep.) alone is present. In this point we again see how the Syrrhaptes, which has 

 this process very small, keeps below the typical Fowls. 



Length of wing-hones in the Syrrhaptes, Pigeon, and Ptarmigan. 



Arm Forearm. Hand, 



in, lin. in. lin. in. I'n. 



Syrrhaptes paradoxus 17 1 10|^ 2 1 



Columba livia 1 9 2 1 2 5^ 



Lagopus scoticus 2 6 2 6 2 5 



This Table shows how near the Syrrhaptes comes to the Pigeon in the comparative 

 shortness of the humerus, and in the length of the carpo-metacarpus and mid digit 

 (PI. XXXVIII. h, dg.) ; in both, the hand is considerably longer than even the fore- 

 arm. In the feeble-winged Ptarmigan, the arm and forearm are of one length ; whilst 

 the hand, on which is inserted the primaries, is a line shorter. I only see two things to 

 distinguish the wing-bones of the Syrrhaptes from those of the Pigeon : the first is that 

 the recess inside the head of the os humeri for the extension of the axillary air-cell, 

 and in the bottom of which the bone is pierced for the admission of air, is larger than 

 in the Pigeon, and approaches what we have seen in the Hemipodius ; the second point 

 (and this may be partly due to captivity) is that the quill-knobs on the ulna (m.) are 

 very faint indeed, whereas in Pigeons they are strong. The humeri alone admit air, 

 as in most of the walking, running, hopping, and perching birds. 



Length of the leg-bones in Syrrhaptes, S^c. 



Femur. Tibia. Tarsus, 



in. lin. in. lin. in. lin. 



Lagopus scoticus 2 8 3 5 1 7^ 



Columba livia 1 6 2 2 1 2 



Syrrhaptes paradoxus 1 6 1 11 10 



Himaiitopus melanopterus ..14 51 47^ 



