SQUAMATA. 1 93 



FIG. 117. 

 DIAGRAM ILLUSTRATING THE PRINCIPAL CHARACTERS OF THE PYTHONOMORPHA. 



A, B. Platecarpw coryphaeus; skull from the lateral and superior aspects, about 

 one-seventh nat. size. U. Cretaceous; Kansas, ag., angular; ar., articular; 

 cor., coronoid; d, dentary; /, frontal; j, jugal; mx., maxilla; na., nasal; 

 orb., orbit; pa. t parietal; pmx., premaxilla; prf., prefrontal; pt., pterygoid; 

 ptf., postfrontal; pto., postorbital; qu., quadrate; s.ag., surangular; s.t., 

 supratemporal (prosquamosal) ; scl., sclerotic; spl., splenial; sq., squamosal; 

 x, exoccipital, etc. (Slightly restored after Merriam.) 



C. Mosasaurus camperi; cervical vertebra, left lateral aspect, one-seventh nat. 

 size. U. Cretaceous; Maastricht, Holland, hy., hypapophysis ; t, trans- 

 verse process. 



D. Ditto; anterior dorsal vertebra, left lateral aspect, one-seventh nat. size. 

 Ibid, t, transverse process. 



E. E'. Ditto; posterior dorsal vertebra, left lateral and hinder aspects, one- 



seventh nat. size. Ibid, t, transverse process. 



F. Ditto ; anterior caudal vertebra, hinder aspect, one-seventh nat. size. Ibid. 

 ch., chevron bone ; t, transverse process. 



G. Edestosaurus dispar; pectoral arch, ventral aspect, one-fifth nat. size. 

 U. Cretaceous; Kansas, co., coracoid; h, humerus; .-<., scapula; ster., 

 calcified sternum. (After Marsh.) 



H. Lestosaurus siinus; pelvic arch, one -thirteenth nat. size. U. Cretaceous; 

 Kansas, fe., femur; iL, ilium; is., ischium; pb., pubis. (After Marsh.) 



I. Mosasaurus lemonnieri; pelvic limb, one-sixteenth nat. size. U. Cretace- 

 ous; Belgium, a, astragalo-central ; c, calcaneum; fe., femur; fi., fibula; 

 t, tibia, i v, the five digits, the fifth represented only by its metatarsal. 

 (After Dollo.) 



W. 13 



