698 



PHYLUM CHORDATA : CLASS REPTILIA 



the typical nine bones are represented, and there is in 

 addition an accessory " pisiform " bone. 



In the pelvic girdle, ilium, pubis, and ischium are 

 represented as usual ; there are both pubic and ischiac 

 symphyses. 



In the tarsus the fibulare and tibiale are united, and the 



distal row consists of only 

 two bones. 



Nervous system. — The 

 brain consists of the usual 

 parts. The cerebellum is 

 small and only partially 

 overlaps the fourth ven- 

 tricle. In the region of the 

 thalamus the epiphysis is 

 distinct and conspicuous, 

 but in the adult the pineal 

 body is quite separated 

 from it, and lies in its 

 connective tissue capsule 

 below the skin. 



Alimentary system. — 

 Small pointed teeth are pre- 

 sent on the maxillae, pre- 

 maxillae, palatines, and on 

 the lower jaw. They are 

 fixed without sockets inside 

 the edge of the jaw-bones 

 (pleurodont) ; in many 

 Lacertilians they are im- 

 planted along the ridge 

 (acrodont). Salivary glands 

 occur on the floor of the mouth cavity. The narrow gullet 

 passes gradually into the muscular stomach, which again 

 passes into the coiled small intestine. Near the com- 

 mencement of the large intestine there is a small caecum. 

 A voluminous liver, with a gall-bladder embedded in it, 

 and a pancreas, are present as usual. 



Embedded in the mesentery below the stomach lies the 

 rounded spleen. A whitish thyroid gland lies on the ventral 

 surface of the trachea a short distance in front of the heart. 



Fig. 409. — Pectoral girdle of a 

 lizard. — From a Specimen. 



I.CL., Interclavicle ; CL., clavicle; ST., 



cartilaginous sternum ; R., rib ; G.C., 



glenoid cavity, formed as always from 



• the ventral coracoid (COR.) and the 



dorsal scapula [SC). 



