or GALLINACEOUS BIRDS AND TINAMOUS. 209 



shown by the artist (PI. XL. fig. 1). The basitemporal region of the Tinamou reminds 

 me of that of the Rails. In front of the basitemporals, at the mid line, the basisphenoid 

 is ridged ; this ridge passes along the rostrum, making it subcultrate : near the end of 

 this elevation there is a small vascular foramen — the only remnant of the pituitary 

 space (fig. I). In typical birds this space is more or less scooped below, and is to some 

 extent often wholly floored by the confluent angles of the basitemporals. This thick 

 pituitary floor, and this subsidiary condition of the basitemporals, is thoroughly stru- 

 thious) ; and there are Mammals, e. g. the Echidna and the Mole, in which these ele- 

 ments (in them called the " lingulse sphenoidales ") bear as great a proportion to the 

 basisphenoid as in the Ostriches. In the Emu, Rhea (PI. XLII. fig. 1, bs.), and Ostrich 

 the basisphenoid shows its junction with the basioccipital on the lower face of the skull ; 

 if hidden at all at the mid line in the Tinamou, it is only very slightly ; whilst in all 

 birds above the " Struthionidse " this is impossible, on account of the secondary floor 

 formed by the basitemporals. A few Mammals, e. g. Myrmecophaga jubata, have retained 

 this secondary skull-floor ; but I am not able to say to what degree the lingulse have 

 contributed to its formation". 



The great posterior pterygoid processes of the basisphenoid are as well developed as 

 in the Ostriches and birds generally ; they are quite rudimentary, although pretty con- 

 stant, in Mammals, and often have the "lingulse" anchylosed to them. They culmi- 

 nate in that most overgrown and extraordinary of all bony centres, the basisphenoid of 

 the bird — a bone the counterpart of which in the Reptilia, e. g. Centropyx, Mocoa, 

 Monitor, Anolis, Anguis, &c., is such a delicate splint, altogether in front of the massive 

 basitemporals ; in the typical Ophidians, however, it is large. 



I mention these things, not for the sake of tediousness, and not by mistake, as wan- 

 dering away from the subject of the affinities of the Tinamou, but simply because this 

 bird has been placed by nature in the great highway of the vertebrate kingdoms, and 

 not in the highway merely, but as it were on the very verge of the " debateable land " 

 where a mixed language is spoken, and where the burning life of the Mammal has 

 lowered down and verges on the half-frozen life of the Reptile. Stretching far away to 

 the right and left of these hot and cold regions of air-breathing vertebrate life is that 

 goodly land, the land of the feathered tribes, where nature sports her virgin fancies, and 

 where neither the Wren, the Nightingale, nor the Turtle want their mate. The Tinamou 

 belongs to the most plebeian tribe of this lovely people, and it has in it also a share of the 

 nature of both those above and those below the class to which it belongs. As in the 

 Rhea (PI. XLII. fig. 1, r.bs.), the "rostrum" of the Tinamou (PI. XL. fig. 1) is ex- 

 tremely large and long — twice the relative length that it attains in the Fowl and in many 

 aerial birds, and a third longer than in the Rails and Plovers (PI. XXXVII. fig. 1, bs.). 



' In the scarcely half-grown Hedgehog (Erinaceus) the " lingulse " are distinct : they are very small, and 

 the large descending plates that form the inner wall of the drum-cavities are exogenous : they are the " posterior 

 pterygoid processes." 



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