196 MR. W. K. PARKER ON THE OSTEOLOGY 



to Plate XXXVI. fig. 2, showing the Syrrhaptes skull. This remarkable prolepsis of 

 the Pigeon's face is combined, however, with two characters which help to make this 

 bird such a paradox. The first character is, that the prevomers (PI. XXXVI. fig. 1) are 

 not at all like those of the Pigeon (PI. XXXVII. fig. 6,pv.), where they are, especially 

 in the Dodo, extremely thick and spongy ; but, instead of this, they are no more de- 

 veloped than in the Grouse (PI. XXXVI. fig. 6), where they are feebler than in almost 

 any other bird. The second character is neither struthious nor columbaceous ; nor is it 

 like what is found in any other kind of bird : this is the nasal septum, which is formed 

 into one large bone in the Sandgrouse (PI. XXXVI. fig. 4). Many birds have this 

 part ossified, but not as one piece, such as this bony plate appears to be. 



Corresponding to the Pigeon-like enfeeblement of the face, the zygoma of the Syr- 

 rhaptes (figs. 1, 2, & 4) is reduced to the last degree of weakness : the posterior process of 

 the prevomer, and the whole of the jugal and quadrato-jugal, together form a bar of 

 bone only like the ossification of a very delicate tendon. 



Feeble as is the mandible (fig. 4), it is nevertheless more that of a Grouse than of a 

 Pigeon ; and, in accordance with the gallinaceous lower jaw, the bend at the mouth- 

 angle is gentle, and not angular and sudden as in the Pigeon (PI. XXXVII. fig. 9, d.) 

 Moreover there is not that disparity, as in the Pigeon, between the lath-like anterior 

 and the spongy posterior moieties of the jaw. The lateral space is wide open also, as in 

 the " Tetraoninse " (PI. XXXVI. fig. 9) — that space which depends upon the tenuity of 

 the dentary forks and the comparative arrest of the " splenial" piece. The angular 

 processes, although arrested, are far in advance of those in the Pigeon (PI. XXXVII. 

 fig. 9, ag.). In conformity with the pinched face, the tongue of the Syrrhaptes is very 

 narrow, as in the Pigeon ; but, true to its Tetraonine relationship, the posterior half of 

 each " cornu minus " is ossified (PI. XXXVI. fig. 5), and these ossicles are united by a 

 bony bridge in front of the hinge with the basihyal ; yet there is a falling-ofF even here, 

 for they do not unite again close behind their cartilaginous free ends as in the Grouse 

 (PL XXXVI. fig. 10). In the Pigeons these " cornua " do not ossify (PI. XXXVII. 

 fig. 10, c.h.) ; in the Lapwing they unite at the mid line, and then there is an azygous 

 bone lying in the tongue, as though it were a true mesial " glosso-hyal " piece 

 (PI. XXXVII. fig. 5, c.h.) ; in reality it is the cerato-hyals in a connate condition. The 

 Syrrhaptes does not agree with the Grouse, Talegalla, Curassow, and Pigeon in having 

 a distinct " uro-hyal"; but it agrees with the Vanellus in having the basi- and uro-hyal 

 in one piece (PI. XXXVII. fig. 5, h.h. u.h.) -. yet the tip of the uro-hyal in the Lapwing 

 is, as in Fowls and Pigeons, a sharp styloid piece ; but in the Syrrhaptes this cartilage 

 (PI. XXXVI. fig. 5) is a mere margin to the spatulate uro-hyal, as in the most typical 

 of birds the Rook. Here we see, then, that the feeblest part of the Sandgrouse's 

 skeleton — this delicate bony skeleton of the arrested second and third poststomal 

 visceral arches of the embryo — yields us all that we could desire with regard to the 

 determination of this bird's affinities. This os hyoides says plainly, that the Syrrhaptes 



