iVo.5.] SHUFELDT ON THE OSTEOLOGY OF EREMOPIIILA. 133 



They extend into the ridge just described. The centra of the dorsal 

 vertebra are somewhat compressed in a slightly increasing degree from 

 before backwards ; each lateral and anterior margin supplies a nearly 

 circular parapophysis for the pleurapophysial capitula, while at points on 

 the posterior margins in the same i)lane we find tlio major share of the 

 notch, which in coaptation of the segments constitutes the subcircular 

 foramina for the exit of the dorsal nerves. 



There is a free pleurapophysis for each dorsal vertebra, but the first is 

 not always connected with the sternum by a sternal rib, as already de- 

 fined ; it sometimes has all the characteristics of a movable cervical rib ; 

 again, when it connects with the sternum, its ha?mapophysis articulates 

 rather high on the costal border (PI. IV, Fig. 22). It may or may not 

 bear an epipleural appendage. 



The vertebral ribs of this Lark articulate, as usual, by tubercula and 

 capitula, with the dorsals, meeting par- and di-apophyses in the ordinary 

 manner. The necks of the ribs in the middle of the series are the long- 

 est, and often we find among the ultimate ones a slight projection be- 

 yond the tubercle, that is received in a corresponding notch at the outer 

 border of the diapophysis it meets. There is but little difference in the 

 width of these flat bones ; perhaps the anterior ones have rather the ad- 

 vantage in this respect. Minute apertures, to allow the air to enter their 

 bodies, are observed in the usual localities. 



The laterally viewed curve of a dorsal rib is barely sigmoidal ; viewed 

 from in front it aj^proaches a portion of the curve of an arc of an ellipse. 



A ridge continuous with the neck is carried down the inner aspect of 

 each bone, to gradually disappear near its middle. The lower extremities 

 of these ribs are slightly enlarged, to afford space for articulation with 

 the sternal ribs ; the surface is convex. 



The epipleural appendages of the dorsal pleurapophyses are conflu- 

 ent with the posterior edges of the bones, and situated below their mid- 

 dles. Occasionally the one in the middle of the series has sufficient 

 length to overlap two ribs ; in young birds of this species they are much 

 shorter, and the best-developed ones show an angle on their inferior 

 borders just after leaving the rib, as if they had left that bone with the 

 original intention of proceeding downwards and backwards at a gentle 

 angle, but suddenly changing mind, j^roceeded directly upwards and 

 backwards at an equal angle ; hence the condition alluded to. 



When the first dorsal rib articulates with the hiemal spine below bj' the 

 intervention of a sternal rib, this latter bone is quite small and delicate, 

 averaging about 3 millimetres in length, and but slightly curved. The 

 remaining dorsal hfemapophyses become longer and more curved as we 

 follow them backwards. They are all flattened from side to side, their 

 lower extremities being abruptly twisted at right angles with their shafts, 

 enlarged, and terminating in a flattened articular surface for the costal 

 border of the sternum. These articular surfaces arc dumb-boll shaped, 

 L e., contracted in their middles. The upper ends of these sternal ribs 



