Modern Text Book of Zoology: Vertebrates

absent air bladder amphibians anteriorly anus aperture arch artery atrial atriopore auricle Balanoglossus birds blood body bone bony brain branchial Branchiostoma buccal cavity called cartilage cartilaginous caudal fin cells Cephalochordata chordates ciliated cloaca coelom developed digestive dogfish dorsal aorta dorsal fin duct eggs elongated endoskeleton endostyle external female fishes folds frog gill slits glands gonads groove heart Hemichordata hemichordates hepatic Herdmania internal intestine kidney larva lateral layer limbs liver lobe longitudinal lungs male mammals median membrane mouth muscles myotomes neoteny nerve cord neural nostrils notochord oesophagus olfactory opening organs ostracoderms pairs pectoral pectoral fin pelvic pelvic fin pharynx placoderms posterior posteriorly proboscis region renal reptiles respiration respiratory scales Scoliodon sensory septum side sinus venosus skin skull snakes snout species spinal spines stomach surface tail teeth tissue transverse trunk urinogenital Urochordata Uromastix valve vein ventral ventricle vertebral column vessel wall