MOEPHOLOGY OF THE GALLINACE.E. 237 



same number of centres as in the Common Fowl, namely, a " lophosteon " in the centre, 

 a pair of pleurostea and a pan- of metostea laterally. 



The third contribution to the osteology of these birds is in my paper " On the 

 JEgithognathous Birds " (Trans. Zool. Soc. vol. ix. plate 54, pp. 294-300). That account 

 of the structure of the palate in Turnix rostrata showed how near these birds come to 

 the lower kinds of Passerine birds ; the palate is almost segithognathous and shows also 

 such vestigial structures as are seen in some other types, especially certain low neo- 

 tropical Passerines, described in the same paper, namely, Aiueretes (ibid, plate 59. 

 figs. 4, 5) and Chasmorhynchus (ibid, plate 62. figs. 5-8). 



This semi-passerine palate, with remnants * or vestiges of the recurrent alinasal 

 cartilages that help to protect " Jacobson's organs " — organs that are suppressed in birds 

 — makes the skull of the Hemipod of extreme interest, and suggests that the place of the 

 bird in the Class is very low ; it is a truly archaic type. Anyhow, the osteology of tliis 

 bird, which has been taken up by me again and again during the last twenty-five years, 

 has lost none of its interest. 



XIII. — The Vertebral Chain of the Chick o/'Turnix rostrata. 



The hind part of this chain is figured (Plate XXV. fig. 5) ; the rest may be here de- 

 scribed. That of the adult is figured in the early paper just referred to. The presacral 

 vertebrae all remain distinct, and are cylindroidal in the dorsal as well as in the cervical 

 region. 



The vertebral formula is as follows : — C. 15, two pairs of ribs free ; D. 4 ; S. 15, two 

 pairs of ribs free; Cd. 6 + 3. The sacrum, divisible into subregions, has 2 dorso-sacrals, 

 3 lumbo-sacrals, 3 sacrals proper, and 7 uro-sacrals, the first two of which have separately 

 ossified riblets (Plate XXV. fig. 5). Pour of the caudal vertebra? are united to form 

 the uropygial piece. 



This chain is very similar to that of the typical Gallinaceous birds ; but it has one 

 more dorso-sacral than the Quail ( Cotumix communis, Plate XXV. fig. 4), and the uropy- 

 gial piece is smaller, and in this the Hemipod comes nearer to the Tinamou (Nothura). 



The atlas and axis have no riblets outside the canal for the vertebral artery ; in this 

 Chick (a week or two old) the rest of the cervicals have riblets, but that on the 3rd is 

 not yet ossified; from the 4th onwards they are small reniform ossicles, with the 

 " hilus " looking backward. The last two have elongated styloid ribs, that of the 15th 

 being nearly as large as that on the 1st dorsal ; and as the first sacral (dorso-sacral) 

 has ribs with a long but not perfect sternal piece, the thorax has actually six pairs of 

 ribs fencing it in. The ribs and these appendages are normal but rather feeble ; the 

 whole space partakes of this feebleness ; none of the processes, upper or lower, being 

 strong or long. This young bird shows well the composition of the sacral and caudal 

 regions ; the proper sacrals are very much extended laterally, as in the Quail (fig. 4), 

 and as in birds generally. The ribs, ever ready to crop up, are absent from the dorso- 



* bee Proc. Hoy. Soc. vol. xliii. 1S88, pp. 397-402. 

 SECOND SERIES. — ZOOLOGY, VOL. V. 36 



