BIRDS. 185 



the top, keeled below, and imperforate, unlike the true Gallinae. The keel is large; it 

 retires very much in the young, but comes well forward in the adult (op. cit., Plate 35, 

 fig. 5, e. s.) ; and the post-costal part of the ento-sternum is a narrow wedge in the adult, but a 

 very broad one in the young (Plate 16, fig. 13, m. x.). Hence the space between the pointed ento- 

 sternum and the long, incurved, pedate, outer bars (e. i. x.) is very large and triangular ; this space 

 answers to the inner notch of the typical Fowl ; and the outer xiphoid of Turnix answers to both 

 the " external" and the " intermediate" xiphoids of the typical form in an undivided state. The 

 costal processes (c. p.) are broad and recurved, and behind them come four condyles ; the last 

 of these receives the sternal rib of the last dorsal vertebra (fig. 13). Behind this there is a floating 

 rib, which belongs to the first lumbo-sacral arch, as in the common Fowl ; but in the typical Fowl 

 and in Crax globicera this floating rib has the rudiment of an abdominal rib continuous with it. 

 This is not seen in Turnix. In Talegalla Lathami there is on each side a much more perfect 

 abdominal rib (Plate XI, figs. 12, 13, a. r. 1); this is only partially segmented from the sternal 

 rib in front of it (which here reaches the Sternum) by a notch in the young, which becomes a 

 fenestra in the adult. On the right side (Plate 11, fig. 13, a. r. 2) there is a small second 

 abdominal rib. The same thing occurs in the Palamedea, with this modification, viz. that 

 there is no abdominal rib at all on the left side. 1 



The ossification of the Sternum of Turnix is ectosteal, as in the Fowl a section of the keel 

 shows this (see fig. 19, magnified twenty diameters, and fig. 18, one hundred diameters). The 

 endosteal deposit (en. o.) is indeed taking place part passu with the ectosteal, but the latter 

 was the first to appear : the former takes place as in the cold-blooded types, that is, the calcareous 

 deposit affects the inter-cellular substance, whilst the cartilage cells become immediately transformed 

 into osseous " lacunae." This ectosteal character of the bony centres is of the greatest consequence, 

 as it keeps our Hemipods safe amongst the Gallostruthious types ; but another, and unlooked-for 

 peculiarity presents itself in the number of these bony patches. Happily for me, these young 

 Hemipods were secured at the same stage of ossification as the Chicks, half a week old, which 

 have been already described : the bony centres were small, and thoroughly distinct (see Plate 

 XVI, figs. 13, 14). Here we see again the " pleurosteon" (pi. o.), the " metosteon" (m. o.), and 

 the azygous " lophosteon" (1. o.) : but the last centre has on each side a new bony patch, which 

 from its relation to the coracoid lips and groove (cr. g.), I propose to call the " coracosteon" 

 (cr. o.). These three entosternal centres are the largest and the earliest, whilst the metosteon is 

 the least and latest. 2 



1 I mention this to show that the Gallinaceous relatives of the Palamedeas are to be sought for 

 amongst the Megapods as well as amongst the Cracinae ; and also the great distinctness of the 

 Hemipod type from the true Gallinje : the Hemipodiine Family is interposed bodily between the 

 Tinatnous and the true Gallinse. As for the Talegalla, the figures above referred to (three fourths 

 of natural size), show how truly Gallinaceous it is with its huge external xiphoid (e. x.) so widely 

 severed from the smaller intermediate bar, as in Crax and Meleagris ; its rostrum also is fenestrate ; 

 a good touchstone of the degree of Gallinaceous affinity. 



! It is worthy of remark that the ossification of the sternum in the Hemipods is very late, 



as compared with the Fowl ; for these young Birds were apparently two or three weeks old ; and as many 



days would seem to bring the deposit to the same stage in the common Fowl. In the Struthionidse 



proper, the centres are much more advanced before hatching (see Plate XVII, figs. 3, 4, and 7) ; but 



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