hatcher: diplodocus (marsh) 



43 



articular surface of the capitulum and tuberculum are smaller. The latter is borne 

 by a very short process, while the capitular process is long and slender. 



The sixth rib is of about the same length, but more slender than the fifth. It 

 is flat throughout most of its length, but triangular proximally. The tuberculum 

 and capitulum are small and the former is sessile while the latter is pedunculate. 



The seventh rib is long and narrow. It is rather stout throughout the proximal 

 two thirds of its. length, but distally it expands into a somewhat broader but thin 

 blade. The tuberculum is sessile and the capitulum pedunculate. They are each 

 circular in outline. 



The eighth rib is very slender. It maintains about the same dimensions through- 

 out its entire length, though the transverse diameter decreases somewhat distally. 

 The tuberculum is nearly sessile, while the capitulum is supported by a slender 

 process. The articular facets are circular in outline. 



The ninth rib differs from the eighth chiefly in its shorter length and more 

 slender proportions. 



The tenth is the shortest of the series. It is elliptical in cross section medially 

 and very much flattened distally. There is a deep cavity on the posterior side be- 

 tween the capitular and tubercular facets. 



From the following measurements it will be seen that the ribs increase regularly 

 in length from the first to the fourth, that the fourth, fifth and sixth are subequal 

 in length, while the posterior ribs decrease rapidly in length from the seventh to 

 the tenth, which is the shortest in the series of free ribs. 



Measurement of Ribs. 



Length of first rib 1057 mm. 43t\ in. 



" second rib, estimated 1300 " 52x\ 



" third rib 1590 " 63| 



" fourth rib 1710 " 68J 



" fifth rib 1727 " 69 



" sixth rib 1680 " 67J 



" seventh rib 1580 " 63} 



" eighth rib 1330 " 53f 



" ninthrib 1140 " 46 



"tenth rib 795 " 32} 



The Coracoid and Scapula. — These are firmly coossified in Diplodocus and enter 

 subequally into the construction of the glenoid cavity. The scapula is much the 

 larger element of the two. Inferiorly it is broad and with a concave external sur- 

 face between the superior border of the glenoid cavity and the anterior border of 

 the widely expanded prescapula. Superiorly and posteriorly the scapula is pro- 



