EXPLANATION OF PLATE XXTIT. 



Figs. 1-14. CJidastcs plan'ifrnna, one-half n.itural size. 

 Fig. 1. Eight iienr.ipophysis of the atlas. 



2. Axis, with odontoiil bone, hypapoiibysis of latter wantins; 2 6, the same, inferior view. 

 Figs. 3-6. Cervical vertebra; in order; a, free hypapophysie, proximal surface; 6, inferior, c, anterior, d, 



superior, and, e, posterior views of the same. 

 Figs. 7-13. Some of the dorsal vertebra; in order; 7 6, the (?) first dorsal from below; e, from in front; 

 and, r, from behind ; 13 h, a posterior dorsal from below; c, front; e, posterior extremity. 

 Fig. 14. Basi-oceipital and part of sphenoid, from below. 



15. Exoccipital, from above and behind. 

 Figs. 16-18. Sironectes angidiferus, one-half natural size. 

 Fig. 16. ? Third cervicil from above, exhibiting zygosphen. 



17. Last cervical, displaying zygautrum; zygosiihenal articulation indistinct, through error of 



artist. 



18. Terminal portion of the articular bone from the outside, showing the suture with the snr- 



angnlar. 



