30 Charles Russell Bardeen 



(Randschleier). There is no pineal gland but the roof of the 

 third ventricle projects inward in such a way as to suggest an 

 inverted pineal gland. It is different from the inversion which 

 accompanies the choroid plexus. The ventral wall of the brain is 

 thick where the optic stalks arise. The infundibulum is large 

 and contains many desquamated cells. The roof of the midbrain 

 is thin, although there are some evidences of the rudiments of the 

 optic lobes. The medulla is relatively normal. A considerable 

 mass of tissue, resembling yolk cells, lies free in the fourth ventricle. 

 The proximal part of the spinal cord is fairly well developed. 

 Posteriorly in places the spinal cord is irregular in form. 



Organs of Special Sense and Peripheral Nerves — On the right 

 side a nasal fossa extends from the nasal pit to the pharynx. On 

 the left side a column of cells with an imperfect lumen does not 

 quite reach the pharynx. Near the pharynx is gives off a lateral 

 process. The optic stalk is patent on each side and the cavity 

 extends between the pigment and sensory layers of the retina. The 

 sensory layer is not specially differentiated. The cornea is closely 

 applied to the front of the sensory layer and lies at some distance 

 from the ectoderm. The auditory vesicles are somewhat simple 

 sacs with dorsal diverticula. The auditory nerve may be fol- 

 lowed into the brain. The sensory ganglia are for the most 

 part fairly well developed. The peripheral nerves cannot be 

 followed. 



Alimentary Tract — There is a free openmg mto the pharynx. 

 This is surrounded by imperfectly developed lips and jaws. On 

 the lips and the jaws are numerous imperfect teeth. Internal 

 gills are fairly well developed on the left side but on the right side 

 forma dense mass fused with the operculum. The opercular cavity 

 does not extend ventral to the pericardium. The oesophagus is 

 nearly occluded by epithelial cells. From it a solid cord of cells 

 passes posteriorly and represents the pulmonary anlage. As the 

 oesophagus is continued into the stomach the alimentary canal 

 swings to the left of the liver and pancreas. The gut then passes 

 to the right across the front of the body, then anteriorly and finally 

 curves back and passes into a portion of the gut which is much 

 distended and extends posteriorly for some distance, then takes 



