length of the gut to the ventral body wall. The other genera 

 of lungfish agree in general with this description. 



EMBRYOLOGiCAL DEVELOPMENT The early stages of develop- 

 ment of the lungfish (Figure 7-13) are like those of the am- 

 phibian with the exception of the spiral valve, which will 

 be described for the following groups. The liver diverticulum 

 arises early. According to Kerr (1919), one dorsal and right 

 and left ventral pancreatic diverticula appear. The dorsal 



diverticulum appears first; it is solid in Protoplerus, hollow in 

 Lepidosiren. The ventral anlagen appear somewhat later and 

 the two buds meet to fuse at the midline dorsal to the stem 

 of the liver diverticulum. Still later the fused ventral mass 

 grows upward to fuse with the dorsal mass which grows 

 backward within the gut wall. The three ducts are retained 

 in Protoplerus. In JVeoceralodiis the left ventral bud remains 

 rudimentary, and the dorsal part comes to drain through 

 the duct of the right ventral diverticulum. 



ventricle 



small intestine 



testis > 

 terminal intestine 



urogenital pore 



bladder (dashed outline) 



urogenital pore 

 anus 



Figure 9-13. Viscera of the salmon. A, ventral view of general mass; B, details of relationships at 

 anterior end of gut; C, ventral view of viscera with fat and lymphoid tissue cleared out; D, section 

 through the ileocolic valve; E, left lateral view of viscera with fat and lymphoid tissues removed. 



266 



THE VISCERA 



