ART. 19 A MIOCENE POEPOISE FROM MARYLAND KELLOGG 51 



Measurements of the right humerus (in millimeters) 



(Greatest exterointemal diameter of lesser tuberosity 18.5 



(Greatest anteroposterior diameter of lesser tuberosity 11. 2 



Greatest exterointemal diameter of epiphysis across lesser tuberosity — 22. 8 



Very few of the ribs are complete, and most of them are fractured 

 in one or more places. The ribs were not disturbed when the slab 

 in which they were embedded was prepared for exhibition and the 

 -whole or portions of 20 ribs are shown (pi. 14) in their original posi- 

 tions. Eight of those on the left side are associated with the corre- 

 sponding dorsal vertebra. Those on the right side of the vertebral 

 ■column lie in a more or less tangled pile. 



Of the ten pairs of ribs the first were the shortest. Judging from 

 those that are fairly complete, the ribs rapidly increase in length 

 from the first (92-94 mm.) to the fifth (207+mm.) and then decrease 

 in length to the tenth (147+mm.). The distal extremities of the 

 first five pairs of ribs are expanded to provide for the attachment 

 of cartilaginous sternal ribs. The capitula of the first to seventh 

 ribs are borne upon long necks, the seventh rib having the longest 

 neck and the first the thickest neck. On the first to fifth ribs, inclu- 

 sive, the capitula are ovoidal in outline. The eighth, ninth, and 

 tenth ribs are single headed. The first seven ribs have capitula 

 which articulate with definite facets on the posterosuperior angle 

 of the centra as well as tubercula which articulate with facets on the 

 extremities of the diapophyses. On the eighth rib the articulation 

 is Avith the diapophysis alone, and on the ninth and tenth with the 

 parapophysis (transverse process). 



The first rib (pi. 14, figs. 1, 10) is short, flattened, greatly ex- 

 panded between the angle and the tuberculum; the capitulum is 

 borne upon a short, thick neck. The tuberculum is larger than the 

 capitulum. The shaft is nearly straight below the angle. The first 

 rib is about three-fifths as long as the second, but the shaft of 

 the latter (pi. 14, figs. 2, 11) is much less expanded between the 

 angle and the tuberculum, and the neck is longer. The right rib 

 ■of the third pair (pi. 14, figs. 3, 12) is more nearly complete than 

 the left. This rib is characterized by a longer and more strongly 

 -curved shaft and the neck is thicker than the second rib. The ex- 

 panded distal extremity is rather wide. Less than half of the 

 right rib of the fourth pair (pi. 14, figs. 4, 13) is preserved and 

 the one on the left side is broken in at least two places. The fourth 

 4md fifth ribs are very similar in most respects, but the latter (pi. 

 14, figf-'. 5, 14) is the longest. The necks of these two ribs are slender 



