34 Charles Russell Bardeen 



Neither optic stalk shows a lumen. The sensory layer of the 

 retina shows much degeneration. The lens rests against it. The 

 auditory vesicles are simple. 



Peripheral Nerves — -The sensory ganglia of the head and the 

 nerve branches may be followed better than in most of the experi- 

 ment larvae. The spinal ganglia and nerves are less definite. 



Alimentary Canal — The mouth is patent and is surrounded by 

 partially differentiated jaws and lips. The internal gills are im- 

 perfectly developed. The operculum extends but a short distance 

 posteriorly. The oesophagus is occluded with cells. Thetracheo- 

 pulmonary process is short and branched. The oesophagus 

 continues to the left into the stomach. The gut curves ventrally 

 to the right in front of the pancreas, then anteriorly on the right 

 of the liver and then bends back in a posterior direction. The 

 liver is well developed and contains large sinusoidal spaces. A 

 very few blood corpuscles appear to be contained in these spaces. 

 There is a large gall bladder. The pancreas is also well developed. 

 The gut, immediately posterior to the pancreas, is greatly distended 

 and beyond the region of distention exhibits several partial coils. 

 The anus is patent. In the body cavity many multi-nucleated 

 cells can be seen. The walls of the body cavity are excessively 

 thick. 



Heart and Blood Vessels — The heart is S-shaped. The ductus 

 arteriosus is solid. There is a small lumen in the ventricle. The 

 sinus venosus is thin-walled. In places blood vessels containing 

 a small amount of blood may be seen, but the vascular system is 

 imperfectly developed. 



Genito-Urinary Organs — The tubules ^of the pronephros are 

 greatly distended and lie in large spaces in which some blood cor- 

 puscles may be seen. The Wolfian ducts are greatly distended 

 near the pronephros but not much more distally. That on the 

 left side is much smaller than that on the right. 



Skeletoji and Connective Tissues — The chorda dorsalis is moder- 

 ately normal in structure. In the sections it is shrunken. There 

 is an excessive amount of connective tissue, especially in the 

 region of the head and in the wall of <:he body cavity. The carti- 

 lages of the head are fairly well developed. , 



