JV'o. 5.1 SHUFELDT ON THE OSTEOLOGY OF EREMOPIIILA. 135 



at their extremities to firm ligaments, that pass directly to the coracoidal 

 capitula above. 



The groove for the coracoids is markedly impressed and continuous in 

 front, extending from costal process to costal process ; its boundaries 

 form the thickest and stoutest part of the bone we are describing. 



The costal processes, possessed of broad bases, arise as thin but prom- 

 inent lamina, upwards, forwards, and outwards, terminated by flattened 

 summits. Their posterior margins bear the costal facets for the articu- 

 lating ends of the sternal hrem apophyses. 



The sides of the body of the sternum on its ventral aspect make an 

 obtuse angle with each other. The line of meeting in the mesial plane 

 is quite evident ; its anterior half is the seat of a row of various-sized 

 pneumatic foramina. There are upon each costal border five, sometimes 

 six, transverse facettes for the sternal ribs ; the shallow depressions among 

 them are scantily supplied with pneumatic foramina. 



The mid-xiphoidal border, in which the keel terminates posteriorly, is 

 thickened; its other boundaries are sharp, with raised ridges below, 

 just within their edges. The greatest length of the sternal body is a 

 little more than two centimetres, and its greatest width a little more 

 than one centimetre, the last measurement taken to the rear of the cos- 

 tal processes. 



Sacral vertehrw and ribs, pelvis, coccygeal vertehrce — (PL IV, Figs. 22, 

 23, and 28). — The first sacral vertebra has become thoroughly confluent 

 with the ossa innominata on either side and with the vertebra behind 

 it. Its diapophyses seem to have spread out upon the under surface of 

 the ilia, combining with them, for we observe that the first sacral pleu- 

 rapophyses articulate in the ordinary manner with the transverse pro- 

 cesses and the parapophyses, the tubercula being situated just near the 

 outer iliac borders. This rib may become, as a rare event, confluent 

 with the pelvis, but is usually free. Its hfemapophysis is the longest of 

 the series, and the articular facette on its lower extremity meets the 

 last facette upon the sternal costal border. This sacral pleurapophysis 

 may possess an epipleural appendage, though it seems to be the excep- 

 tion. 



The second sacral rib is a delicate hair-like bone of uniform thickness, 

 that does not show any decided tubercle, merely, after leaving the ver- 

 tebra, coming in contact with the under surface of the ilium, on each 

 side, for the entire interspace between the tubercle and head. It, too, 

 may become confluent with the pelvis on its lower surface. 



Extending downwards and forwards by a gentle curve, it meets its 

 hsemapophysis through a miniature articulation. This latter style articu- 

 lates along the posterior border of the sternal rib of the first sacral 

 pleurapophysis, never reaching the costal border, and the second sacral 

 rib never bears an epipleural spine on its posterior border. 



The sacral vertebrae are invariably confluent throughout the chain in 

 the pelvis of the Horned Lark ; indeed, it is only by a process of staining 



