REPTILES AND AMPHIBIANS 



lizard the body is dry and hard, the epidermis being 

 converted into regularly arranged scales, while there 

 are no glands in the skin except at the beginning of the 

 thighs, where a row of pores void on to the exterior 

 the secretion of the femoral glands. The limbs of the 

 amphibian are short and only four- toed, rot much 

 used in locomotion. Those of the lizard are five- toed 

 and longer, and very much used in locomotion. On 

 the neck of the menobranch will be noticed three 

 pairs of fringed red outgrowths of the body, which 

 are the gills ; by means of these the animal at least 

 partially breathes. It has also lungs. Close to the 

 gills are, on each side of the neck, two perforations 

 which lead into the pharynx ; these are the so-called 

 gill clefts. In the lizards we find not the slightest trace 

 of these last two structures. The animal has only 

 lungs, with which alone it breathes. If we dive into 

 the anatomy of the two animals we shall emerge with 

 other characters, which completely distinguish them. 

 The skull of the Menobranchus is fixed on to the vertebral 

 column by two joints or condyles while there is but 

 one median condyle in the lizard. The heart is three- 

 chambered in both ; but in the amphibian the origin of 

 the aorta from the ventricle is dilated into a thicker 

 walled tube, in which are several series of valves regulat- 

 ing the flow of the blood when it leaves the heart to 

 pass through the arterial system. In the lizard there 

 is no such dilated " conns arteriosus" and the persist- 

 ence of this conus in the amphibian is a mark of its rela- 

 tionship to the lower lying fish, where such a conus always 

 exists. The menobranch has no sternum or breast-bone 

 formed by the union of the ribs ventrally ; there is such 

 a sternum in the Lacerta. The Menobranchus lays eggs 

 as does the Lacerta ; but the eggs of the former are smaller 

 than those of the latter, and do not contain nearly so 

 much yolk. Moreover there is no hard shell such as 



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