TllK KIi;8 AND STEKNUM. 



131 



The ril)s l)cliiii(l the second gTiuhially increase in lengtli, and become 

 more curved. The head remains hir<^-e, and its articidar faces are usually 

 separated from each other, as shown in tii;ures 12!)-132, below. 





\\\ 



Figure r2;i.— Autciior rili of Dinocera.? mirabik. Marsh (Nu. 1212); postprior view. 

 Figure 13ij. — Tlie same rilj ; inner view. 

 FiGURS 131. — The same rib ; front view. 

 Figure 132. — The same rifj ; pro.ximal end. 

 h. head ; t. tnbercle. 



All tlie figures are oue-foiirth natural size. 



