The Dogfish as a vertebrate

Deals with the Dogfish as a typical vertebrate, illustrating its anatomy in detail. Comparisons with four other types are given; i.e., with newt, lizard, bird and rabbit. Fishes, amphibians, reptiles, birds and mammals included in vertebrates; basic plan demonstrated by Dogfish. Alimentary canal has mouth, oesophagus, stomach, intestinal colonic regions; liver and pancreas; also central nervous system, sense organs. Detail from Dogfish; comparisons in the other four types (frog, lizard, bird and rabbit). Skeleton - axial and appendicular - common to all. Respiratory system involves large surfaces for oxygenation of blood - gills, lungs. Ventral position of heart; plans of blood systems. Gills as embryonic vestiges. Urinogenital systems association. Sexual reproduction and separate sexes common to vertebrates; detail for Dogfish (internal fertilization), Frog (external fertilization).