^'^'- ^^'^'1 Shufeldt, Material for a Study oj the Megapodtider. 187 



Finally, the last six vertebra; all extend their diapophyses to 

 the inner iUac margins ; they become shorter and shorter from 

 before backwards, and gradually more and more at right angles 

 to their centre — the length of the transverse processes pro- 

 gressively shortening as the skeleton of the tail is approached. 



Sternum and Shoulder-Girdle (figs. 42, 43, and 44). — There is a 

 very evident Gallinaceous modelhng in all of tliese bones in the 

 Mateo, and especially in the elements of the pectoral arch. Vox 

 example, the big os furcula is a typical U-shaped bone, with large 

 subqviadrilateral hypocleidium directed backwards. Its superior 

 ends are but very shghtly expanded, and each articulates with the 

 coracoid and scapula of its own side. 



A coracoid is a long, straight bone, which gradually expands 

 and flattens towards its sternal end. Its outer lower angle is 

 truncate, with a somewhat conspicuous tuberosity at its upper 

 outer angle. From the posterior lower half of the flat shaft the 

 surface is marked with muscular ridges. In articulation, the 

 coracoids appear to meet in the coracoidal grooves, in a foramen 

 piercing the base of the manubrium of the sternum. Superiorly, 

 the coracoidal head is not especially tuberous, while mesiad it 

 hooks over in order to articulate with the free end of the clavicle 

 of the same side. 



A scapula is a large bone of imusual lengtli, for in the articulated 

 skeleton it reaches back to a point posterior to the anterior part 

 of the pelvis. Its blade is fiat and smooth, being truncate at its 

 distal extremity, and dilated for its middle third. As usual, it 

 contributes about one-third of the articular surface for the 

 glenoid cavity — the coracoid furnishing the balance. 



The sternum is a short bone of no unusual width ; its carina or 

 keel is very deep anteriorly, but vanishes graduaHy to a point in 

 the mid-posterior plane behind. Its lower border is thickened ; 

 the " carinal aijgle " very prominent, and the anterior border 

 greatly concaved backwards (fig. 42). This border is double 

 above, from the manubrium to the middle point below, after 

 which, to the carinal angle, it is very sharp. 



The manubrium does not project far to the front, its lower part 

 being a thin, median plate, to dilate above to a thickened portion, 

 the upper surface of which is co-extensive with the upper surface 

 of the sternal body. Between the " costal grooves " the plate-like 

 portion of the manubrium is pierced by a foramen. Dorsad, the 

 body of the sternum is concaved, with a large median pneumatic 

 foramen at the juncture of anterior and middle thirds. 



Either " costal process " is rather conspicuous, being much 

 roughened upon its outer aspect, but smooth internally. 



There is a pair of enormous elliptical " notches " on either side 

 of the keel in the xiphoidal end of the bone, and these give rise to 

 five conspicuous processes. The median one is co-extensive witli 

 the keel, and is formed like an isosceles triangle, with the apex 

 and the distal end of the carina in the same point. 



The inner pair of xiphoidal processes are of moderate width 



