38 Charles Russell Bardeen 



Alimentary Canal — The mouth is open. Lips and jaws are 

 rudimentary. The pharynx is dilated and contains a sac-like 

 protrusion through its floor from the pericardial cavity (section c). 

 The gills are rudimentary and are contained within a cavity on 

 each side w^hich is formed by an opercular fold open behind (sec- 

 tion d). The oesophagus has a lumen into which irregular vesicular 

 spaces open. The tracheo-pulmonary process is short. The gut 

 passes to the left of the liver and pancreas, then curves across the 

 body in front and finally extends straight back. The lumen is 

 not distinct. Neither liver nor pancreas is well differentiated 

 The body cavity is greatly dilated. 



Heart and Blood Vessels — ^The heart is an S-shaped tube. The 

 ductus arteriosus and ventricle are thick-walled; auricle and sinus 

 venosus are thin-walled. There is a slight amount of blood in the 

 lumen. The pericardial cavity projects into the mouth, pushing 

 the floor of the pharynx ahead so that the heart comes to lie literally 

 in the mouth. The only definite blood vessels are two vessels 

 which appear to be posterior cardinal veins. These are dilated 

 and anastomose with one another in several places. 



Gentto-Urinary Organs — -The tubules of the pronephros are 

 greatly dilated. The Wolfian ducts are irregular in form. That 

 on the right side appears to be missing in places. 



Skeleton and Connective Tissues — The chorda dorsalis is appar- 

 ently normal. There is an excessive amount of connective tissue. 

 Some of the cartilages of the head are fairly well differentiated. 



Musculature — Some of the muscles of the head are fairly dis- 

 tinct. The myotomes are moderately normal, although in places 

 the muscle cells are somewhat scattered. 



Skin — In the region of the head there are especially large 

 masses of projecting epithelium (section a). 



Larva No. 8, Experiment II 



External Form — The long axis is fairly straight. The general 

 appearance is that of a normal embryo soon after the tail has 

 grown out. The tail, however, is somewhat shrunken. The 

 sucker is fairly normal. 



