178 



THE VERTEBRATE SKELETON. 



-10 



12 



FlG. 28. A, VENTRAL VIEW OF THE CRANIUM J B, LATERAL VIEW OF THE 



CRANIUM AND MANDIBLE OF Siphonops aimulatus (after WIEDERSHEIM). 



1. anterior nares. 



2. naso-premaxilla. 



3. frontal. 



4. parietal. 



5. maxilla. 



6. vomer. 



7. orbit. 



8. quadrate united with 



pterygoid in front. 



9. squamosal. 



10. exoccipital. 



11. dentary. 



12. angular. 



13. basi-occipital and basisphe- 



noid fused. 



14. posterior narial opening sur- 

 the rounded by the palatine. 



X. pneumogastric foramen. 



