318 



THE AMERICAN MUSEUM JOURNAL 



do we get even so much as a connected 

 chapter, most of our knowledge being 

 based on scattered pages or odd sen- 

 tences torn here and there from the 

 book of time. 



Anyone who has seen a fur seal in his 

 native haunts has no difficulty in believ- 

 ing him to be descended from some 

 bearlike beast; but it seems a far cry 

 from a sea cow, or a fishhke porpoise, 

 to any land-frequenting quadruped, and 

 the best evidence we have so far lies in 

 the traces of the hip bones and small 

 vestiges of the limbs, which, though 

 buried in the body, still lie where they 

 should if they are the representatives 

 of former limbs. 



It would of course be one link in the 

 chain, one step toward a four-footed 

 animal, if we could find a four-paddled 

 porpoise, but none has yet come to light, 

 and here is where the sea cow comes for- 

 ward with an important bit of evidence. 

 When palaeontologists w'ere hunting in 

 the Fayum, Egypt, for ancestors of 

 existing elephants, they came upon 

 remains of a manatee, not unlike those 

 of today, save that it possessed four 

 well-developed paddles; and because 

 it was so evidently the predecessor of 

 the modern sea cows, it was named 

 Eosiren. 



Today the sea cows are a scattered 

 race; one species of manatee inhabits 

 the rivers of western Africa, another 

 those of northern and eastern South 

 America and parts of Florida. Onedu- 

 gong occurs on the east coast of Africa 

 and in the Red Sea, while a near relative 

 is found on the northern coast of Aus- 

 tralia where it is hunted for its oil. 



Those interested in sea cows from a 

 zoological standpoint will find that they 

 display considerable diversity both ex- 

 ternally and internally. Thus, the du- 

 gong is clad in a smooth leathery skin; 

 the hide of the manatee suggests that of 



an elephant, while the covering of the 

 rytina is said l)y Steller to have re- 

 sembled bark, being so thick that it was 

 hewn off with axes. Steller also says 

 that the creature was so helpless that it 

 was rolled about by the surf and banged 

 against the shore, so it would seem that 

 such a hide was a necessary protection. 



The dugong has a broad forked tail, 

 not unlike that of the porpoise, while 

 the tail of the manatee is rounded. 

 The rytina was absolutely toothless, 

 while the manatee has, during its life- 

 time, a series of eleven teeth on either 

 side of each jaw, and these are replaced 

 from behind, as in elephants, and not 

 from below, as in the vast majority 

 of mammals. The dugong has two 

 tusks so deeply imbedded in the skull 

 (which is bent sharply downward in 

 front) that they seem of little practical 

 use. 



In one particular all known sea cows 

 agree; their bones are extremely dense, 

 being almost ivory-like in texture in our 

 own manatee. In this species too, the 

 ribs reach their maximum size, being so 

 large as almost to touch one another, 

 with the result that the skeleton is 

 extremely heavy. This weight of bone 

 is believed to serve the same purpose 

 as the ballast tanks of a submarine and 

 to enable the animal to browse readily 

 on aquatic plants. The skeleton is 

 lightest in the sea-going dugong, though 

 even in this species the bones are heavy 

 in comparison with those of land ani- 

 mals. 



The lungs, in the manatee at least, are 

 long and narrow, and though of small 

 capacity suffice to keep the animal 

 afloat so that the nostrils are just above 

 water. Aside from these more appar- 

 ent characters, there are peculiarities 

 of heart, backbone and hip bones which 

 are of more interest to the anatomist 

 than to the axeraire observer. 



