postorbita 



paroccipital process 



epiphysis extracolumella 



columella 



epibranchiol II 



pibronchiol I 



stapes 



'/ \internal process 



ceratobrcnchiol I 



ceratohyol 



lingual process 



copula hypohyal 



Figure 4-3. Ventrolateral view of skull; A, with hyoid apparatus in position and detail of columella; 

 B, as seen in ventroposterior view. 



pineal bod/ 



quadrate cartilage^/^>X 



B 2.5, 



lateral wall of otic capsule 

 occipital arch 



basidorsals of vertebrae 



notochord 



ascending process 

 trabecula communis 



occipital arch 



interorbital septum. 



Meckel's cartilage 



2.25 mm 



interorbital septum 



sphenethmoid 

 commissure 



nasal tectum 



notochord 



orbital cartilage 



otic capsule 



metotic fissure 

 hypoglossal foramina 



-notochord 



Meckel's cartilage 



parachordal plate 



C 4, 



ascending process (epipterygoid) P''° °"*ot'ca 



pila metoptica 



otic capsule 



pila metoptica 

 pila preoptica 

 amino orbitonasalis 



taenia marginalis 

 quadrate 



poroseptal cartilage 



dorsal process 



hypohyal 



ceratohyol 



columella 



A*.. ■■ occipital arch 



notochord 

 cerotobranchials 



D 5, 



5.2 mm 



Figure 4-4. Several stages in the development of the chondrocronium of the lizard, tacerfo. 

 A, lateral view of head, 2.5 mm in length, with first skeletal condensations; B, rudiments of head 

 cartilages at 2.5-mm head length as seen in dorsolateral and slightly anterior view, otic capsule of 

 left side removed; C, head length of 4 mm as seen in B; D, skeleton at head length of 5 mm. as 

 seen in lateral view; E, slightly larger than D as seen in lateral view. (After DeBeer, 1937) 



OTHER TETRAPODS • 67 



