52 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. GO 



and curve upward to the extremity; the tiiberciila are ovoidal in 

 outline and are broadest at the posterior end. A considerable por- 

 tion of the sixth rib (pi. 14, figs. 6, 15) on the right side is missing 

 and tJie one on the left side is for the most part concealed by 

 matrix. The shaft of the sixth rib is more slender than any of the 

 preceding, the capitulum is smaller and more nearly circular, and 

 the ^^uberculum is pyriform in outline. The shaft of the seventh 

 rib (pi. 14, figs. 7, 16) is much narrower than any of the preced- 

 ing, resembling the eighth in this respect; the extremity is thin, 

 but there is a distinct surface for the attachment of a cartilaginous 

 sternal rib. The eighth, ninth, and tenth ribs have a single facet at 

 the proximal end and slender shafts which are slightly bowed. All 

 of these posterior ribs are rather thin at the distal end, with one 

 face flattened and the other more or less convex. The eighth rib 

 (pi. 14, fig. 8) has a more elongate capitulum than either of the 

 folloT\3ng ribs. 



Measurements of the ribs {in millimeters) 



