Amia and Lepisosfeus The stomach of A mm is large and 

 sacculate, with a distinct posterior caecum (Figure 9-16). 

 That o[ Lepisosleus is an elongate tube which posteriorly hooks 

 to the right and forward to its pyloric valve. Lepisosleus has 

 a mass of tubular pyloric caeca underlying the gut and 

 opening into the posteroventral aspect of the intestine just 

 behind the pyloric valve. Amia lacks pyloric caeca. In both 

 genera the intestine is divided into anterior and posterior 

 segments. The posterior segment is not separated by a valve 

 from the elongate, looped anterior portion, but contains a 

 spiral valve, which in Anna makes four turns and in Lepisos- 

 leus about two and a half turns in a counterclockwise direc- 

 tion as one follows it posteriorly. In both, the spiral valve 

 ends on the right wall of the intestine a short distance an- 

 terior to the anus 



The liver is a single, elongated piece below the stomach in 

 Lepisosleus; it is a bilobed mass in Anna, with the left lobe 

 the larger. In both, the gall bladder lies to the right above 

 the pyloric intestinal loop. The pancreas is diffuse. There is 

 a distinct pancreatic strand along the bile duct in Amia 

 which extends into the medial dorsal surface of the liver. 

 This band continues back from the bile duct along the dor- 

 sal surface of the gut. In Lepisosleus the pancreas is more dif- 

 fuse and not separable from the lymphoid and fatty tissue 

 scattered among the loops of the gut. 



The spleen lies to the right of the stomach in Amm and 

 has a long lobe which extends back above the terminal part 

 of the anterior segment of the intestine. In Lepisosleus the 

 spleen is two-parted, lying in a position comparable to that 

 of Anna. In both genera there are strands and masses of 

 lymphoid tissue along the gut and in the mesenteries. 



liver 



air bladder 



gall bladder. 



spleen 

 lymphoid tissue 



'osa efferentia 



stomach 



pyloric caeca. 



two-parted spleen< 



first loop of intestine 



spiral valve- 



spiral valve 



-Ovary 



.liver 



-Stomach 



.pyloric region of stomach 

 pancreas 



lymphoid and pancreatic tissue 



scales around anus 



urogenital opening 

 anterior margin of anal fin 



Figure 9-16. Ventral views of viscera of Amia, A, and Lep/sosteus, B. 



270 • THE VISCERA 



