Description of Plate 22. 



A. Right side, seen from inside. 



1. Sphenopalatine muscle. 



2. Spheno-pterygoid muscle. 



3. Sphenoid crest. 



4. Anterior temporal muscle, man- 



dibular portion. 



5. Posterior temporal muscle, man- 



dibular portion. 



6. Supermaxillary bone. 



7. Mandibular bone. 



8. Poison fang. 



9. Palatine bone. 



10. Internal pterygoid bone. 



11. External pterygoid bone. 



12. Parietal bone. 



13. Squamosal bone. 



14. Quadrate bone. 



15. Premaxillary bone. 



16. Prefrontal bone. 



17. Post-orbital process. 



B. Right side, seen from outside. 



1. External pterygoid muscle. 



2. Posterior portion. 



3. Spheno-palatine muscle. 



4. Spheno-pterygoid muscle. 



5. Posterior temporal muscle, man- 



dibular portion. 



6. Anterior temporal muscle, man- 



dibular portion. 



7. Supermaxillary bone. 



8. Mandibular bone. 



9. Pit. 



10. Fang. 



11. Internal pterygoid bone. 



12. Palatine bone. 



13. Parietal bone. 



14. Post-orbital process. 



15. Prefrontal bone. 



16. Premaxillary bone. 

 17.^ Quadrate bone. 

 18. Squamosal bone. 



C. Head of water mocassin {Ancistrodon 

 piscivorus) seen from above. Skin 

 removed except near snout. 



1. Poison gland. 



2. Ending of the anterior temporal 



muscle in capsule of poison 

 gland. 



3. Mandibular portion of anterior 



temporal muscle. 



4. Attachment of the middle tem- 



poral muscle to the tempo- 

 parietal region of cranium. 



5. Posterior temporal muscle. 



6. Internal suspensory ligament of 



poison gland. 



7. Posterior ligament. 



8. External pterygoid muscle. 



9. Digastric muscle. 

 10. Poison fang. 



n. Pit. 



12. Shield scales. 



13. Eye. 



14. Cervical muscles. 



D. Right side, seen from outside. 



1. Poison gland. 



2. Duct of poison gland. 



3. Internal suspensory ligament of 



gland. 



4. Posterior suspensory ligament. 



5. Anterior temporal muscle. 



6. Insertion of anterior temporal 



muscle around the poison 

 gland overlapping from behind 

 and ending in the capsule. 



7. Posterior temporal muscle, man- 



dibular portion. 



8. Posterior temporal muscle, cra- 



nial portion. 



9. Middle temporal muscle, at- 



tachment to the parietal bone. 

 The fibers end in a fan-like, 

 spreading layer over anterior 

 temporal muscle. 



10. External pterygoid muscle. 



11. Origin of the external ptery- 



goid muscle. 



12. Spheno-palatine muscle. 



13. Digastric muscle. 



14. Supermaxillary bone. 



15. Internal pterygoid bone. 



16. Mandibular bone. 



E. Right side, seen from inside. 



1. Poison gland. 



2. The duct of poison gland. 



3. Mandibular portion of the an- 



terior temporal muscle. 



4. Upper portion of the anterior 



temporal muscle enveloping 

 posterior region of gland. 



5. Cut edge of the middle tem- 



poral muscle. 



6. Middle temporal muscle; the 



upper torn edge is detached 

 from the parietal bone to 

 which it has been inserted. 

 The lower cut edge is originally 

 continuous with the fibers 

 shown in the opposite cut edge 

 through a short piece of the 

 removed portion. 



7. Posterior temporal muscle. 



8. Upper portion of the posterior 



temporal muscle. 



9. External pterygoid muscle. 



10. Its anterior portion. 



11. Spheno-pterygoid muscle. 



12. Spheno-palatine muscle. 



13. Digastic muscle. 



14. Internal suspensory ligament. 



15. A portion of posterior ligament 



of poison fang. 



