18 GENERAL ANATOMY OF THE FROG 



is soft and fleshy, but is slightly stiffened by a car- 

 tilaginous plate the body of the hyoid. 



b. The tongue, which is thin and fleshy, is attached to 

 the front part of the floor of the mouth, and has its 

 free bilobed end turned backwards towards the throat. 



Turn ike tongue forwards with the forceps. 

 C. The glottis, or aperture of the larynx, is a longitudinal 

 slit in the floor of the posterior part of the mouth, 

 and is stiffened laterally by the arytenoid cartilages. 

 Pass bristles through the glottis into the lungs. Ij 

 any difficulty is experienced in finding the glottis 

 snip through the angles of the mouth loith scissors, 

 so as to allow the mouth to be opened more widely. 



C. The Abdominal Viscera. 



Lay the frog on its back under water, and fasten it down to 

 the dissecting board by pins through the limbs. Cut through t/ie 

 skin, along the middle line, the whole length of the ventral sur- 

 face. Separate the skin from the underlying parts, noticing its 

 very loose attachment to these parts, and the large sj)ace a lymph 

 cavity beneath it. Turn the Jlaps of skin outivards, and pin 

 them back. Notice : 



a. The muscles of the body-wall. 



b. The pectoral or shoulder girdle : a bony arch running 



across the body, opposite the fore limbs. 



Pinch up with forceps the muscular body-wall, and cut through 

 it into the body-cavity or codom with scissors a little to each side 

 of the median line, being careful not to injure the anterior abdo- 

 minal vein which runs along the inner surface of the body-wall 

 in tJuit line. 



Continue the cut of one side backwards to the hinder end oj 

 the body, and forwards to the jaw, culling through the pectoral 

 girdle with strong scissors, and taking care not to injure the parts 

 beneath. 



Tie ligature-thread twice round the anterior abdominal vein, 

 cut between the two ligatures, and turn back the two halves of the 

 vein in the body-watt. 



