ABDOMINAL VISCERA 23 



the other viscera, are outside the abdominal ccelomic cavity. 

 (See Fig. 2, p. 19.) 



a. The ureters, or ducts of the kidneys, are a pair of white 



tubes arising from the outer edges of the kidneys at 

 about a quarter of their length from their hinder 

 ends, and running back to open into the dorsal wall 

 of the cloaca, opposite the opening of the bladder. 



In the male frog a pouch -like dilatation, the 

 vesicula seminalis, is present on the outer side of 

 each ureter, close to its opening into the cloaca. 



b. The adrenal bodies are small yellowish-red patches on 



the ventral surface of the kidneys. 



c. The corpora adiposa, or fat bodies, are two bright 



yellow tufts of flattened processes attached to the 

 dorsal wall of the body cavity ; they vary much in 

 size, and usually come to the surface just behind 

 the liver. 



2. The Spleen is a small round dark-red body lying in the 

 mesentery, opposite the commencement of the large intestine. 



G. Thyroid and Thymus. 



1. The thyroid is a small paired gland attached to the 

 base of the external jugular vein, a little way in front of the 

 heart. 



2. The thymus is a small ovoid paired gland behind the 

 tympanum. It can be seen by reflecting the hinder border 

 of the tympanum forwards and removing the adjacent muscle 

 that lowers the mandible. (See p. 59.) 



