ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 295 



1. That Myxine never attacked living fish on the lines, but preferred fish recently- 

 living to stale fish. They did, indeed, attack the latter, thus disproving the assertion 

 of the fishermen. I agree, however, with the fishermen that Hags never attack living 

 free swimming fish, and are therefore not parasites. 



2. As indicated by the slime, the Hags enter the fish by the gills rather than 

 by the mouth. This, doubtless, to escape the teeth. When the fish were hauled up the 

 Hags could be seen sticking out of them in all directions, and great numbers were 

 lost by escape through the mouth. Only a few came out through the gills. 



3. The body cavity was usually entered dorso- laterally. The liver was eaten first, 

 then the gut and heart, and finally the flesh between the skin and backbone was 

 attacked at the posterior end of the body cavity, the Hags working forwards until 

 the dorsal muscles were entirely devoured. The whole operation takes about two 

 hours. 



4. In a dying or feeble fish the Hags stop the action of the gill cover by blocking 

 it with slime. As soon as the motion of the operculum ceases, they enter the body 

 through the gills. 



5. It was invariably noticed that in the region of the back the Hags did not 

 touch the spinal nerves, which looked as if they had been roughly dissected out. This, 

 t believe, is not due to any preference for muscle, but simply owing to the peculiar 

 character and action of the dental apparatus, which would rasp away the muscle and 

 leave the stringy nerves. 



The respiratory current in Myxine is easily demonstrated in the living animal by 

 placing a few grains of eosin in front of the nasal aperture. Almost immediately 

 water discoloured by eosin will be seen issuing from the branchial apertures. The 

 respiratory current is a constant and steady stream, and there is only occasionally 

 a sharp discharge from the gills. 



Myxine can evidently distinguish light from darkness. When a number were 

 placed in a large tank with one dark end, all the more active and healthy fish 

 migrated to the dark end, and invariably returned there when brought back. 



B. Nasal Aperture and Mouth. 



The nasal aperture is relatively very large, as in PalsBospondylus, and is median, 

 dorsal and terminal. It is compressed from side to side, and is overhung above by a 

 prominent forwardly projecting lip-like process. On each side of the latter is a short 

 anteriorly projecting pointed tentacle for anterior touch, and below and in front of it, 

 but at the side of the nasal aperture, is another and similar tentacle on each side. 

 In the living animal the latter tentacle juts out almost at right angles to the long 

 axis of the body and somewhat downwards, and is for lateral touch. 



The mouth is circular and sub-terminal. There are no obvious jaws. It is 

 situated on the ventral surface behind and below the nasal aperture. In both dead 



