488 REPTILES. 



DIAGRAM XXIX. 

 Reptiles. 



Head (after Nuhn) shews the fangs and fang-sheaths of a venomous 

 serpent. 



Croc, (after Wiedersheim) is a ventral view of a crocodile's skull ; 

 Pmx. premaxillae, M. maxillae, PI. palatines, Pt. pterygoids, p. n. 

 posterior nares ; Q. quadrate, B. o. basi-occipital, Orb. the orbit, Ts. 

 OS transversum,^;^. jugal, Qj. quadrato-jugal. 



Circ. (after Nuhn) is a diagram of the heart and associated blood- 

 vessels in the tortoise ; s. v. i. the superior venae cava;, i. v. c. the 

 inferior vena cava, r. a. right auricle, r. v. righthalf of ventricle, r.p.a. 

 and /. /. u. right and left pulmonary arteries, p. v. pulmonary veins, 

 /. 11. left auricle, /. v. left half of ventricle, aortic trunk (r. a.) giving 

 origin to right aortic arch (r. a. ), and to subclavians [s. cl. ) and carotids 

 {c), I. a. left aortic arch from the right ventricle, d. a. the dorsal aorta 

 formed from the union of the two aortic arches, cal. the coeliac artery 

 from the left aortic arch. 



The figures named Gird, (after Gegenbaur) represent the pectoral 

 girdles of lizard [B.) beneath, and tortoise (A.) above. 



In the pectoral girdle of the lizard are shewn : — sc. scapula, cor, 

 coracoid, cl. clavicle, i. cl. ipter-clavicle, st. sternum. 



In the pectoral girdle of the tortoise are shewn : — sc. scapula, cor. 

 coracoid,/. co. " pre-coracoid. " 



