48 ELEMENTARY BIOLOGY. [CHAP. 



canal, at that point at which it receives the urino- 

 genital ducts. 



Examine its lining membrane ; it is for the most 

 part identical with that of the large intestine ; that 

 of its terminal third has the characters of the inte- 

 gument. 



h. The 2U'ctcrs {iirinoi^cnital ducts ^. Cf. Sect. F. 3); 

 their openings will be seen as two minute orifices, 

 on the dorsal wall of ^., situated close together and 

 surrounded by tumid lips. 



c. The bladder ; a median ventral diverticulum of a.^ 

 having no direct communication with the ureters. 



E. The cavity of the mouth and the respiratory organs. 



I. Use tlic specimen dissected above. Cut the ali- 

 mentary canal across immediately in front of the 

 liver, and retain the anterior portion. Pin down 

 under water ventral surface uppermost ; enlarge the 

 mouth opening by cutting through the sides of the 

 buccal cavity witli a pair of scissors : pull down the 

 lower jaw and pin it back. 



a. The two internal openings of the nasal cavities 

 {posterior ?iares); near the anterior end of the roof 

 of the mouth. 



l>. The openings of the Eustachian recesses ; situated 

 far back near the angles of the jaw. 



c. The teeth ; confined to the upper jaw and roof of 

 the mouth. 



a. Tlie maxillary teeth; forming a parallel series, 

 set along the inner face of the whole upper jaw. 



