128 ILLINOIS STATE ACADEMY OF SCIENCE 



The special attention of the writer is drawn to that 

 portion of the capsule which forms the posterior wall. 

 In the work of Higgins (1920) the term planum tectale 

 is used to designate that same portion of the capsule 

 which Gaupp in his discussion of the lizard has called 

 planum antorbitale, a term continued in use throughout 

 this discussion. Regarding the use of the term antorbi- 

 tale, the writer recalls the fact that in all the nasal cap- 

 sules of the amphibia, where the facts are known, the 

 antorbital process arises from the trabecula as a lateral 

 diverticulum just posterior to the choana. Subsequently 

 this structure unites with other portions of the capsule 

 to form this posterior wall. In the reptiles there is no as- 

 sociation between these two regions, and it would seem 

 that the structure known as planum antorbitale could not 

 have arisen as a normal antorbital process, and conse- 

 quently the use of this term is questioned. 



BIBLIOGRAPHY. 



1900 Gaupp, E., Das Chondrocranium von Lacerta agilis. Ein Beitrag 

 zum Verstandniss des Amniotenschadels. Anat. Hefte. Abth. 

 1 Bd. 15. 



1920 Higgins, G. M., The Nasal Organ in Amphibia. Illinois Bio- 

 logical Monographs, Vol. VI, No. 1. 



1912 Kunkel, B. W., The Development of the Skull of Emys lutaria. 

 Jour. Morph. Vol. 23. 



1878 Parker, W. K., On the Structure and Development of the Skull 

 in the common lizard. Phil. Trans. Royal Soc, Vol. 170. 



EXPLANATION OF PLATES. 



Fig. 1. Anterior view of model of nasal capsule of Natrix cyclopion, 



63 mm. X58. 

 Fig. 2. Dorsal view of model of nasal capsule of Natrix cyclopion, 



63 mm. X58. 

 Fig. 3. Lateral view of model of nasal capsule of Natrix cyclopion, 



63 mm. X58. 

 Fig. 4. Cross section through tectum nasale of Natrix cyclopion, 



63 mm. X35. 

 Fig. 5. Cross section through vomeronasal capsule of Natrix cyclo- 

 pion, 63 mm. X35. 

 Fig. 6. Cross section through nasal concha of Natrix cyclopion, 



63 mm. X35. 

 Fig. 7. Anterior view of model of nasal capsule of Natrix cyclopion, 



75 mm. X58. 

 Fig. 8. Dorsal view of model of nasal capsule of Natrix cyclopion, 



75 mm. X58. 



