NATURAL SCIENCES OF PHILADELPHIA. 227 



Clavicle proximally simple ; mesosternum anchor-shaped. Xiphisternum 



with two, sometimes one fontanel le. 

 Mandible with angular process. 

 Tongue papillose, simple. 

 Toes not opposable, all directed forwards. Agamidse, Hatteriidae. 



PLEURODONTA. 



Iguania. 

 Temporal bone superior plate not developed beyond arched body. 

 Frontal not under-arching olfactory lobes. 

 Arches complete ; not covered by dermoossification. 

 Articular and angular separate. Dentary produced posteriorly, not covering 



coronoid. Meckel's cartilage wholly or in part covered. 

 Premaxillary single. Suspensoria two. 

 Clavicle with simple proximal ends.* 

 Mesosternum anchor-shaped 

 Tongue papillose, simple. Anolidae, Iguanida. 



DlPLOGLOSSA. 



Temporal bone superior plate developed beyond arched body. 

 Frontal not under-arching olfactory lobe. 

 Arches complete, temporal fossa covered by dermoossification. 

 Articular and angular separate. 



Dentale not produced far posteriorly. Meckel's cartilage covered. 

 Premaxillary single. Suspensoria two. 

 Clavicle with simple proximal ends. 



Mesosternum cruciform or rarely simple. No Xiphisternal fontanelle. 

 Tongue papillose, sheathed at tip. Supranasal plates numerous. 

 A n g u i d , Gerrhonotidse, Helodermidae. 



Thecaglossa. 



Temporal bone superior plate developed beyond arched body. 



Frontal under-arching olfactory lobes. 



Arches not complete ; fossa not covered by dermoossification. 



Articular and angular separate. 



Dentary short, not developed posteriorly. Meckel's cartilage exposed in its 



groove. 

 Premaxillary single. Suspensoria two. 

 Clavicle with simple proximal end. 

 Mesosternum anchor-shaped. 

 Tongue smooth, sheathed at base. V a r a n i d &. 



Leptoglossa. 

 Temporal bone superior plate developed beyond arched body. 

 Frontal with a larger or smaller ridge on each side of olfactory lobes ; no 



arch. 

 Lateral arches complete. 

 Articular and angular separate. 

 Dentary, lower posterior process often short, often long. Groove for Meckel's 



cartilage mostly overarched. Suspensoria two. 

 Premaxillary single or double, without exterior marginal foramen. 

 Clavicles proximally much dilated, usually perforate or enclosing a foramen. 

 Mesosternum cruciform ; not more than one pair of supranasal plates. 

 Tongue squamous or obliquely plicate. 



* The transverse limb of the raesosteruum, extending to the angle of the clavicle, gives an ap" 

 pearance in some of the Basiliseiuae of a proximal foramen. 



1864.] 



