Note at the anterior end of the toad a wide transverse slit, the _mouth_. What other openings are on the anterior end? Note the two large _eyes_, the organs of sight. Just back of each eye note an elliptical, smooth membrane. This is the tympanum of the outer _ear_, and through this membrane the vibrations produced by sound-waves are transferred to the inner ear, which receives sensations and transmits them to the brain. Open the mouth by drawing down the lower jaw. Note just within the angle of the lower jaw the _tongue_. How is it attached to the wall of the mouth? On the tongue are a great many fine _papillæ_ in which is located the sense of taste. It has now been seen that most of the special senses of the toad have their seat in the head. Pass a straw or bristle into one of the nostrils. Where does it come out? These internal openings to the nose are the _inner nares_. Note in the roof of the mouth just posterior to each of the eyeballs an opening. These are the internal openings to the wide _Eustachian tubes_, which lead to the mouth from the chamber of the ear behind the tympanum. Note far back in the mouth an opening through which food passes. This is the _œsophagus_ or _gullet_. Note just below this gullet an elevation in which is a perpendicular slit, the _glottis_. This is the upper end of the _laryngo-tracheal chamber_, and the flaps within on either side of the slit are the _vocal cords_. Note at the posterior end of the body in the median line an opening. This is the _anal opening_ or _anus_. Note the general make-up of the toad. How do its arms compare with our own? How do its fore feet (hands) differ from its hind feet? Note that the body is covered by a tough enveloping membrane, the _skin_. In the skin are many glands which by their excretion keep it soft and moist. =Internal structure.=--TECHNICAL NOTE.--With a fine pair of scissors make a longitudinal median cut through the skin of the venter from the anal opening to the angle of the lower jaw. Spread the cut edges apart and pin back in the dissecting-pan. Note the complex system of _muscles_ which govern the movements of the tongue. Observe a number of pairs of muscles overlying the bones which support the arms. These are attached to the _pectoral_ or _shoulder-girdle_. Note the large sheet of muscles covering the ventral aspect of the toad. These are the _abdominal muscles_, which consist of two sets, an outer and an inner layer. Note that posteriorly the abdominal muscles are attached to a bone. This is the _pubic bone_ of the _pelvic girdle_ which supports the hind legs. TECHNICAL NOTE.--With the scissors cut through the muscles of the body wall at the pubic bone and pass the points forward to the shoulder-girdle. Separate the bones of the shoulder-girdle and pin out the flaps of skin and muscle to right and left in the dissecting-pan (see fig. 1). Cover the dissection with clear water or weak alcohol.