CATFISH AND EELS. 183 



EELS. 



Observations from the " Iconographic Encyclopaedia.'' 

 " Petromyzontid^. This family, the last of the Der- 

 mopteri, is also without lateral fins : a continuous median fin 

 is formed by the coalescence of the dorsal, caudal, and anal. 

 Respiration is generally performed by means of fixed gills, 

 the lateral openings to which are seven in number on each 

 side. A single nostril is placed on the top of the head. The 

 principal forms belong to the genera Peiromyzon or true 

 Lamprey Eel, and Ammocsetes, or Sand Lamprey. The former 

 have a circular mouth provided with numerous teeth, and 

 fringed with ciliae to assist the animal in attaching itself to 

 the bodies of its prey. The mouth is a true sucker, adhesion 

 being effected by atmospheric pressure. Fishes of various 

 kinds are not unfrequently caught bearing the bloody circular 

 scar produced by the bite of the Lamprey," and quite often 

 the Lamprey itself. The Catfish, or Pimelodus, appears to be 

 especially liable to such attacks. The Lampreys attain to 

 great size, and are highly prized by some nations. The love 

 borne them by the ancient Romans is a matter of classical 

 history, and at the present day they are the favorite food of 

 epicures. 



" The Miirsenidde or Eels, with the normal structure of 

 the gill apertures, yet have them very small and capable 

 of being completely closed. The body is serpentiform, 

 and although provided with scales, these are scarcely ap- 

 parent, being embedded in a thick mucous skin. The air- 

 bladder is polymorphous, and the intestines without coeca. 

 The Eels, in their different species, are inhabitants of both 



