OF GALLINACEOUS BIRDS AND TINAMOUS. 193 



and are bent downwards outside the canal for the internal carotid artery. The basi- 

 temporal plane is relatively twice as wide as in the Pigeon and Plover (Pi. XXXVII. 

 figs. 1 & 6, b.t.) ; and although only the outer half of each moiety is anchylosed ante- 

 riorly to the true basisphenoid, yet the whole anterior margin of the coalesced basi- 

 temporals sends forward a free and slightly everted lip. In the Grouse these parts 

 are only free where the Eustachian tubes meet below the pituitary space. Externally 

 the basisphenoid and basitemporals are anchylosed, and the line of union is bevelled over 

 and smooth : a similar state of things is seen in the Pigeon and the Plover. Moreover 

 the region mesiad of this line of junction on each side is open in the Syrrhaptes to a 

 much wider extent than in the skulls of its congeners ; and the Eustachian tubes do 

 not open close upon each other as in typical birds. This divergence of the bony Eusta- 

 chian trumpets is combined in the Syrrhaptes with several other most unmistakeable 

 struthious characters. 



As in the Ostrich-group, the true basisphenoid is of great breadth where the anterior 

 pterygoid processes grow out; and, as in them, the " rostral process " (PI. XXXVI. fig.l) 

 is enormous, as it is in all the Struthionidse ; and in this little bird it is for some extent 

 as thick as in the huge Curassow (Crax globicera). But histologically these parts are 

 very Pigeon-like in the Syrrhaptes. The strong pedicles (anterior pterygoid processes) 

 are in Syrrhaptes much larger than in the Lapwing (PI. XXXVII. fig. 1, b.s.), and even 

 than in the Common Pigeon (PI. XXXVII. fig. 6, b.s.) ; they are nearly as large 

 actually as in Columba palumbus : in the " Struthiones " they grow to their utmost 

 size. They always grow out on each side the pituitary space, as thickenings of the 

 roots of the trabeculce cranii, and are externad of, and just anterior to, the openings 

 of the Eustachian tubes. They are closest to these openings in the Struthionidse, and 

 somewhat freer from these passages in typical birds. The small, neat, forwardly placed 

 pterygoids of birds are in great contrast to the long rambling osseous pieces which 

 answer to them in reptiles. In the Syrrhaptes, the Tinamou, and the Ostriches, the 

 pterygoids have a strongly reptilian character ; but the gradation is complete from the 

 Fowl and the Pigeon, through the Syrrhaptes and then through the Tinamou, to the 

 Ostriches. In the Emeu the posterior end of the pterygoid is wedged between the 

 anterior pterygoid processes and the os quadratum : in the true " Gallinse," typical, 

 subtypical, and aberrant, the anterior third of the pterygoid articulates on its inner 

 side by a somewhat raised and margined facet with the long and low anterior ptery- 

 goid process. In Hemipodius this facet on the pterygoid has crept further back, and is 

 shorter ; in the Pigeon (PI. XXXVII. fig. 6, p.g.) it is on the middle of the bone, 

 and is much smaller ; it is smaller still, and also in the middle of the pterygoid, in 

 the Lapwing (PI. XXXVII. fig. \,p.9-). In the bird now under consideration, the Syr- 

 rhaptes, the facet is again large, and is placed at the junction of the middle with the 

 posterior third of the bone; then in the Tinamou it has crept nearer the os quadratum; 

 in the Rhea (PI. XLII. fig. 1 a.pt. & p.g.) nearer still: and so we get a perfect series 



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