60 DESCRIPTIONS OF PREPARATIONS. 



last retain only the upper division of the transverse processes, which are 

 present also in all the remaining sacral vertebrae. The ligaments uniting 

 these processes ossify, and a flat subcutaneous area (absent in Ratite birds) 

 is thus formed. To the lumbar succeed two sacrals, homologues of the 

 vertebrae so named in Lizards, &c. In some specimens of the Pigeon, both 

 of them carry a pair of stout bony rods or ribs visible only from below. 

 These ribs are not free. They swell at their distal ends which fuse to 

 the outer ends of the transverse processes (upper division) of their own 

 vertebrae and coincide with the widest part of the area mentioned above, 

 and lie therefore just internal to the acetabulum. Either the first or the 

 second pair of these ribs may be absent. Behind the sacral vertebrae 

 comes a variable number of caudal vertebrae, termed for distinction's sake 

 * uro-sacrals.' The free caudal region contains seven to eight vertebrae. 

 They have no articulating processes. The last is thin, compressed, and 

 up-turned. It is known as ' pygostyle ' or ploughshare bone (os en soc de 

 charrue), and represents four to six fused vertebrae. 



The five pairs of ribs consist of ossified vertebral and sternal sections. 

 Each vertebral section articulates only with its own vertebra : the first four 

 bear uncinate processes united to their posterior borders. These processes, 

 as in Hatteria, Iguana and the Crocodile, are pre-formed in cartilage. The 

 last sternal section unites with its predecessor, not with the sternum. The 

 sternum covers nearly the whole abdomen and has a deep concave internal 

 surface. There are four borders : an anterior bearing the rostrum in its 

 centre with a coracoid groove on either side and ending laterally in a costal 

 process ; a right and left costal border deeply concave and bearing the 

 ribs ; and a posterior or xiphisternal border. This border is convex, of 

 great extent, and interrupted, as in some other Birds, on either side the 

 median line by an outer xiphisternal notch and an inner xiphisternal 

 fontanelle the inner notch of the Fowl tribe. Notch and fontanelle are 

 in the living bird closed by membrane probably substituted for original 

 cartilage. The border presents accordingly five processes two outer, two 

 intermediate, and one median. The convex outer surface of the sternum 

 carries the keel or carina, whence comes the name Carinatae, applied to the 

 vast majority of living birds as opposed to the Ostrich and its allies, known 

 as Ratitae from the raft-like aspect of the keel-less sternum. 



The shoulder girdle consists of a scapula, coracoid, and furcula 1 . The 

 scapula is sword-shaped and thin. There is no separate suprascapula. 

 A small conical process internal to the glenoid facet represents the meso- 

 scapula or acromion. The coracoid is firmly united by ligament to the 

 scapula. A prominent clavicular process rises in front of its glenoid facet, and 

 there is a thin curved subclavicular, or subscapular process ( = praecoracoid), 



1 This word is often, but incorrectly, written Furculw/w. It is written Furcula in Bronn's Klass. 

 und Ordn. des Thierreichs, vi. Abth. 4 by Selenka, without the mention of any other form. 



