312 CHORD ATA. 



The median olfactory sac has been noted. The paired 

 eyes are present but scarcely functional, whilst 

 the paired auditory sacs are small and contain 

 only one semicircular canal. 



The kidneys are paired organs lying in the dorsal part of 

 the coelom. They consist of coiled tubules communicating 

 u 'tai ^^^^ ^^ exterior by paired ureters beside the 

 anus. The gonad is simple and produces 

 sperms in the young individual and eggs at a later period. 

 Hence Myxine is a protandric hermaphrodite. There are 

 no genital ducts. 



Fig. 225. — Median Sagittal Section through Myxine 

 Glutinosa X \. {Ad nat.) 



Nasal Sac. Internal Nas. Opening of 



Brain. I Gill-Pouch. Nerve Cord. Notochord. 



Tongue. -,___- 



Gill-Pouch. "* I Heart. Liver. 



Branchial Artery. 



The eggs are large, oval, and have much yolk. They 

 Development ^^^ enveloped in capsules which have hooks at 

 ' each end and are usually found embedded in 

 slime. The development is unknown. 



Myxine shows a number of very primitive vertebrate 

 features, of which we may specially note the absence of 

 paired fins, vertebral column, pancreas, spleen, sympathetic 

 nerves and genital ducts. The unpaired nasal sac, the 

 peculiar pituitary pouch with its internal aperture, the ear 

 with a single semi-circular canal, and the hermaphrodite 

 condition are also unique characters amongst Vertebrata. 

 With the lampreys it constitutes the class Cyclostomata, a 

 name emphasising the suctorial condition of the mouth. 



