PROF. W. K. PAEKEK ON ^GITHOGNATHOUS BIRDS. 299 



this is the anterior extremity of the true " inferior turbinal " (i. tb). This turbinal is 

 shown in the next section at its fullest development (fig. 6, seen from behind), a mere 

 foot-shaped outgrowth from the little extended "aliseptal" region, this part being 

 almost aborted by the huge nostril-covers (alse nasi). We shall see that in the Rook 

 the " inferior turbinal " infolds itself two and a half times, in the Fowl twice, in the 

 Rhea (" Ostrich Skull," pi. 10. figs. 14 & 15) and in the Tinamou (ib. pi. 15. fig. 9, tb) 

 three times, whilst in the " Casuarinse" (ib. pis. 10. & 12) this fold breaks up so as to 

 be a veritable " arbor vitee " in section. In this section (fig. 6) the septum (s. n) is thin- 

 ning out towards the hinge ; the alinasal wall is coiling inwards and thickening, still 

 having its huge turbinal flap {a. tb) ; close behind this part the long submesial flap is 

 tied strongly to the vomerine cartilage (fig. 8, lower view). The floor-flaps (»./) 

 are very large here ; near their end their strongly bowed inner faces are very close 

 together. 



The next section (fig. 7) is viewed from behind ; and the left antorbital plate or " pars 

 plana " {p. ]}) is cut away : it is very large, as is shown on the other side. Between 

 the alar and median parts of the fast-hardening ethmoid {]}. e) and the antorbital 

 wall there is a large open space, admitting the ingress of both first and fifth nerves 

 (1, n. n). 



This ecto-ethmoidal cartilage (upper ethmoid and pars plana) appears on the surface 

 above and laterally; hence the abortion of the lachrymal, as in the Passerinte. 

 There is nothing to be called " upper turbinal " (u. tb) except the circular infolding of 

 the aliethmoid (al.e) just in front of the antorbital wall; and the " inferior turbinal" 

 shows a greater curvature just in front of that wall. The " middle turbinal " is only 

 represented by a somewhat ridgy condition of the great posterior plate, between the 

 other two. Having studied these parts in the highest Amphibia {Sana) and in the 

 Snake, Lizard, Crocodile, and Turtle, I am enabled to say that the " TurnicomorphEe," 

 although formed on the ornithic plan, yet have their nasal labyrinth very little in ad- 

 vance of what is seen in those cold-blooded types, and considerably below that of the 

 " saurognathous " Woodpeckers. The postoral region presents a peculiarity which can- 

 not be passed over, although the plan of the present paper does not strictly include 

 those parts. 



In my former Plates of these birds I figured in H. varius a large tympanic (" Gallina- 

 ceous Birds and Tinamous," pi. 35. figs. 1 & 2), and in the other species (pi. 34. figs. 1 

 & 2) a larger and a smaller bone ; but in this invaluable skeleton, lent me by Mr. 

 Salvin, I find six (PI. LIV. fig. 12, ti/) ! and the last but one of this chain is much the 

 larger, and is folded upon itself like a viper's tooth, as if to enclose some tube. I am 

 not certain whether the " siphonium," which carries air into the lower jaw, is embraced 

 by this bone or not ; in my next instance it is, as I will soon show. 



Considered by itself, the Hemipode is a low type of the " Carinatse," more reptilian 

 in some respects than the " Ratitae " down below it. But if it be looked at as a remnant 



2s2 



