Class IV. CETACEOUS FISHES. 59 



viz. two pectoral fins, and one back fin ; but in 

 some species the last is wanting. 



Their tails are placed horizontally or flat in 

 respect to their bodies ; contrary to the direc- 

 tion of those of all other fishes, which have them 

 in a perpendicular site. This situation of the 

 tail enables them to force themselves suddenly 

 to the surface of the water to breathe, which 

 they are so frequently constrained to do. 



Many of these circumstances induced Lin- 

 tubus to place this tribe among his Mammalia, 

 or what other writers style quadrupeds. 



To have preserved the chain of beings entire, 

 he should in this case have made the genus of 

 Phocce, or Seals, and that of the Trichecus or 

 Manati, immediately precede the whale, those 

 being the links that connect the Mammalia or 

 quadrupeds with the fishes ; for the Seal is, in 

 respect to its legs, the most imperfect of the 

 former class ; and in the Manati the hind feet 

 coalesce, assuming the form of a broad horizon- 

 tal tail. 



Notwithstanding the many parts and proper- * 

 ties which cetaceous fishes have in common with 

 land animals, yet there still remain others, that 

 in a natural arrangement of the animal kingdom, 

 must determine us, after the example of the 



