4 o 4 



MANUAL OF ZOOLOGY 



SECT. 



internally by a longitudinal septum. A pulmonary artery, 

 carrying blood to the lung or lungs, is given off from the 

 afferent branchial system. The blood is returned from 

 the lung or lungs by means of a pulmonary vein, which 



c 



nick 



FIG. 229. Ceratodus Forsteri. Lateral view of the anterior portion of the 

 skeleton. A, anterior median membrane-bone of the roof of the skull ; B, 

 posterior median membrane bone. bas. basal cartilage of the pectoral fin ; br. 

 branchial arches ; int. inter-operculum ; lain, plate overhanging branchial 

 region ; inck. Meckel's cartilage ; occ. rb. occipital rib ; op. operculum ; pal. 

 palato-quadrate ; pet. pectoral arch ; rbs. ribs ; sub. orb. sub-orbital bones ; sq. 

 squamosal ; supra, sc. supra-scapula. 



opens into the left division of the sinus venosus, and 

 through it reaches the left division of the auricle. 



CLASS III. AMPHIBIA 



The larvae of the Newts or Efts, and those of the Frogs 

 (familiar to everyone under the name of tadpoles) bear a 

 close resemblance in form and movements to the Fishes. 

 But, as they approach maturity, these fish-like larvae 

 undergo a metamorphosis, fitting them for the amphibious 

 mode of life which gives its name to the class : penta- 



