EXPLANATION OF PLATE XIX. 



Vertebras of Pyfhovomorpha : of Clidastes tortor and Plateiarpus icta-icus, one-half natural size. 



Frfi. 1. Clidastes tortor, atlas centrum. .. 



2. Ditto, axis: a, from the side; b, from behind. 



3. Third cervical vertebra : a, from behind ; b, from before ; c, from below ; d, from the side. 



4. Cervical more posterior: a, from below, showing free hypapopbysis attached and crushed; 



b, from behind. 



5. Cervical vertebra behind the last figured, from behind ; a, from before. 



6. Posterior dorsal vertebra: a, from behind ; b, from iu front; c, from below. 



7. Platecarpus ictericus, axis vertebra, from behind. 



8. Third vertebra: a, from behind; 6, from below. 



9. A posterior cervical : a, from front; b, from below; c, from behind. 



10. Last cervical : a, from front ; b, from below. 



11. Radius or fibula of a small Clidastes from Fossil Spring Canyon ; a, the inner edge of the same. 



