482 CLASS MAMMALIA. 



correctly, they are without feet, having but two arms with 

 which they row, fight, and nurse the young. These two 

 arms may be compared to the two pectoral fins of fish from 

 which they differ however in their composition. Instead 

 of being formed of radii connected by a membrane, they 

 consist of bones, muscles, and tendinous flesh, and are 

 covered by a thick skin. They have a clumsy appearance, 

 looking like a sort of flattish sack with a pointed termina- 

 tion. They are more or less long, and more or less wide, 

 according to the different species, having however in all a 

 sufficient extent to perform the office of very strong and 

 active oars. The insertion of their base with the body is 

 more or less near the commissure of the lips. 



Independently of the two pectoral fins, most of the 

 Bahena? have, in common with the fishes, a dorsal fin, the 

 forms of which differ, and which is situated either at a 

 greater or less distance from the orifice of the spiracles, or 

 from the extremity of the tail. The Common Whale has 

 no such thing. 



The tail of the Balsenae, strong, flexible, and rapid in its 

 movements, is augmented at its extremity by a broad 

 horizontal fin, composed of two oval lobes, which by their 

 union produce a crescent, and each of which possesses a 

 power of rapid and varied motion, and an independent 

 action. These lobes are so long in some, that from the 

 end of one to the extremity of the other, is a distance of 

 three-sevenths of the length of the animal. This tail so 

 powerful an auxiliary both in swimming and in combat, is 

 the substitute of the hinder extremities of other Mammalia. 



If these fins give some resemblance to Balaena with the 

 class of fishes, and seem to remove it from the mammifera, the 

 organs which serve for the re-production of species indicate 

 its close affinity with the latter. The parts of generation 

 in both sexes are strictly conformed on the mammiferous 

 type, and in the female, on each side of the vulva, at a 



