182 SHOULDER-GIRDLE AND BREAST-BONE. 



Sub-ordo" GALLING." 

 Examples.- Phasianus colc/iicus, Linn.; P. yattus, Gmel. ; Numida meleagris, Linn. 



For a description of the Shoulder- and Breast-bones in the adult Gallinaceous Bird I must 

 refer the reader to ray paper in the 'Zoological Transactions' for 1864, vol. 5, pp. 149 241. * 



I see no reason for modifying the classification used in that paper (see p. 155) ; with regard 

 to the Tinamine Sub-order, when these Birds have acquired a Gallinaceous skull and pelvis, and 

 when their long intermediate xiphoids have acquired an outer fork ; then, and not till then, 

 can they be classified otherwise than as a Gallo-struthious group ; they appear to be a sort of 

 Ostriches intermediate between the Apteryx and the Ekea in the act of passing into the 

 Gallinaceous territory, by way of the Hemipods. Nevertheless, these Birds undergo an amount of 

 metamorphosis, which forbids them from being placed with the typical Struthionidse, and yet they 

 retain an abundance of true Struthious characters, leaving them in the closest vicinity with 

 those low and, as it were, embryonic or Reptilian types. 1 As to the Shoulder-girdle and 

 Sternum of the typical Gallinaceous Bird, my earliest illustrations are from the common 

 Pheasant, that is, after nine days of incubation (see Plate XVI, figs. 2 7 ; figs. 2 and 4 are mag- 

 nified six diameters; fig. 3 twenty-four diameters; and figs. 5 7 forty diameters). The 

 scapula (fig. 4, sc.) is narrow, blunt at its supra-scapular end, which part is somewhat recurved ; 

 the rest of the bar being gently arcuate. Half the bar is enclosed by an endosteal sheath, and this 

 is nearer the small blunt acromion (m. sc.) than the distal end. A clearly defined transverse cleft 

 has already severed the scapula from the coracoid (cr.) ; this passes through the shallow glenoid 

 fossa (gl.). The head of the coracoid is greatly extended forwards, and its shaft, already enringed with 

 a delicate bony layer, is very narrow; its broad, flat, six-sided epicoracoid region (e. cr.) is, like 

 its head, still unossified. There is some delicate cartilage near the end of the acromion, this is 

 the " meso-scapular" segment (m. sc. s.) ; another patch, lunate in shape, is severed from the pro- 

 jecting head of the coracoid; this is the "proximal prse-coracoid segment" (p. cr.). Neither of 

 these acquire much consistency, the former becoming rapidly ossified from the end of the clavicle 

 (see fig. 5, m. sc. s., cl.), and the latter becoming converted into the ligament which ties the 

 clavicle to the coracoid. Below the junction of the clavicles there is a double layer of delicate 

 fibro-cellular stroma ; this is more transparent than ordinary connective tissue in its nascent con- 

 dition ; but it never becomes converted into true hyaline cartilage. This mass, into which the 



1 It will be seen that I have changed the nomenclature of the parts ; and with regard to the 

 bones of the Shoulder especially, many newly discovered elements have to receive names in the present 

 paper. I have retained the term " ento-sternum " for all the mesial part of the breast-bone ; for 

 " episternal process," I use the term "rostrum;" for " hyo-sternum," " costal process " and " costal 

 region ;" to the " hypo-sternum " of former papers, as well as to the terminal part of the ento-sternum, 

 I now apply the term " xiphoid process." With regard to the ossific centres, their nomenclature is entirely 

 new ; and some of them, viz., the two " coracostea/' and the " urosteon," are now described for the 

 first time. 



2 Professor Huxley (' Proc. Zool. Soc.,' 1867, p. 425) puts these inosculant forms into a sepa- 

 rate Sub-order, namely, the Dromaeognathse : his views will be seen to coincide very closely with mine. 



