176 MR. W. K. PARKER ON THE STRUCTURE AND 



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losis has taken place in some degree. In both the perpendicular ethmoid is continued 

 on into the septum nasi, the whole being one bone, reaching from the exit of the optic 

 nerves to no great distance from the solid part of the intermaxillary. No distinction 

 between the upper and vertical ethmoid can be seen, and in T. robustus the aliethraoid, 

 pars plana, and basal part of the inferior turbinal have coalesced with each other, and 

 with the antorbital plate of the lacrymal, thus agreeing with the Apteryx. In T. varie- 

 gatus, however, the boundaries of all these parts can be clearly seen as fine sutures 

 (Plate XV. fig. 13), the upper and perpendicular part (eth., p.e.) only having lost their 

 distinctness. In one important point the stouter kind (T. robustus) difiiers from the other, 

 and approaches the typical birds, viz., in the commencement of the great ethmo-septal 

 cleft (Plate XV. fig. 8, c.f.c), by which the upper jaw is allowed to be hinged in to 

 the head. All birds go through the struthious stage in their embryonic condition, and 

 at a further stage agree with this Tinamou. In T. variegatus, so nearly allied, this 

 cleft does not appear; this shows the importance of not drawing our conclusions too 

 hastily, and of the necessity for suspecting mere negative evidence — the " instance con- 

 tradictory" may turn up in the hundredth species*. There is a very regular posterior 

 nasal zone, in which ossification takes place freely (Plate XV. fig. 13, eth., a.i.t.); on a 

 sudden it stops, and then all the rest, save the axis and a little of the roof, or roots of 

 the inferior turbinals, is cartilaginous ; yet in T. robustus some dendritic bony threads 

 creep forwards into these cartilages ; there are no true upper and middle turbinal out- 

 growths; and the ossified part of the inferior turbinal is closely conjoined to the front of 

 the outstanding part of the "pars plana" (Plate XV. fig. 13,^9.^., al.s.) ; its upper part 

 is vertical, and nearly parallel with the perpendicular ethmoid {p-e.), thus moving 

 upwards to join the slanting overhanging aliethmoidal lamella (Plate XV. fig. 13, al.e.), 

 the only rudiment of the upper turbinal mass and cribriform plate of the mammal. 

 Anteriorly, this lamella, where it grows out of the septum nasi, becomes the outer nasal 

 wall and root of the inferior turbinal (Plate XV. figs. 9, 13, al.s.); it passes nearly 

 halfway down in a convex manner, and then becomes double, the outer plate forming a 

 new convexity, and the inner turning upwards and inwards to coil rather more than 

 twice (Plate XV. fig. 9, it.b.). Further forAvards its coil is only one and a third (fig. 10), 

 and then in the alinasal region, when the alse are free of the septum, it simply passes 

 inwards and a little downwards, but like the alinasal of the Rhea, its outgrowth is a 

 little more labyrinthic than the inferior turbinal, for it gives ofi" the rudiments of 

 three other plates (Plate XV. fig. 11). The complication of these turbinal growths in 

 the alinasal region is an interesting character. I must refer to my other paper for a 

 description of the facial structures of the Tinamou, merely remarking that the anterior 

 part of the palatine (Plate XV. fig. 'i, pa.) is much shorter in T. variegatus, and that 

 the metapterygoid process of the os quadratum {q.) is much broader (ralline) than in 



* As far as I have seen there is no " mesopterygoid " in the typical " Struthionidae," nor in Tinamus varie- 

 gatus and robustus; an "instance contradictory" turns up, however, in T. bmsiliensis sive major, where it is 

 very large, and permanently distinct. * 



