THE EEL FAMILY. 401 



and straighter than in the Sharp-nosed species ; gape large. Pectoral 

 fins and origin of back-fin placed nearer the head than in any other 

 of our fresh-water species. Colours : general colour above olive-green, 

 passing into a lighter green, and thence into a yellowish white. 



The vignette below gives a representation of a struc- 

 tural peculiarity noticed in the tail of the Eel. It con- 

 sists of a pulsating organ, or " lymphatic heart " as it has 

 been termed, which beats more rapidly than the proper 

 heart of the animal, and the purposes of which have not 

 hitherto been clearly recognized. A similar organ has 

 been remarked in the Frog, the Toad,, the Salamander, 

 and the Green Lizard, and I have also observed it in the 

 tail of the young fry of the Salmon when a few days old. 





LYMPHATIC HEART IN THE TAIL OF AN EEL. 



