IOWA ACADEMY OF SCIENCES. 99 



above conditions seem to l)e fiillilled in tlie case of the walrus (Odobn'iius 

 rosmarus). This species will then stand for our point of departure. 



2nd. The gregarious habit of the walrus offers a constant opportunity 

 for a departure from the path of monogamous rectitude. This fact is well 

 illustrated in human affairs by the great amount of social immorality found 

 among the crowded tenements of our large cities. Constant opportunity 

 offers the most powerful temptation to gratify desire, and this is doubtless 

 as true among Pinnipedia as among men. The result of this is a departure 

 from strict monogamy in the direction of promiscuity.*! The harbor seal 

 [P/ioca viUdina) illustrates this stage in the process. So far as I can ascertain, 

 this species is simply promiscuous in sexual affairs, but does not attain to 

 polygamy in the sense used here. The sexual disparity is slight, the males 

 being somewhat heavier, and but little, if any, longer than the females. 



3d. The departure from monogamy in the direction of promiscuity 

 results in constant rivalry on the part of the males to possess the most 

 attractive, or the greatest number, of the females. Rivalry begets warfare, 

 the world over. This pui'ely individual and personal rivalry among the 

 male Pinnipedia results in individual combats, in which courage, fcrocitj-, 

 and size are the controlling factors. We thus have instituted the most rigorous 

 kind of sexual selection, by means of which the above desirable qualities are 

 secured, propagated, and intensified on the part of the males. The females, 

 on the contrary, seem to be practically passive. The writer has been unable 

 to find any evidence that the female Pinnipedia exercise any choice in the 

 matter of accepting or rejecting individual successful males. The sexual 

 selection thus instituted is true sexual selection as defined by Darwin as 

 follows: "This [sexual selection] depends on the advantage which certain 

 individuals have over other individuals of the same sex or species, in exclu- 

 sive relation to reproduction.'"' It differs, however, from a vast majority 

 of instances of sexual selection in apparent absence of choice on the part of 

 the female. 



This stage in the development of polygamy is illustrated by the hooded 

 seal ( Cystophora cristata), which appears to be promiscuous in sexual matters, 

 and in which the males fight fiercely for the possession of the females. The 

 divergence in sex has become considerable, as already indicated, the males 

 being more than twice as heavy as the females. 



4th. The struggle for the possession of the females having become a fixed 

 and intensified habit, and the sexual disparity continuing to grow more 

 pronounced, the following results might be expected: 



(((} The larger and lustier males would have their desire greatly intensified 

 and their sexual powers appreciably increased. 



(6) The smaller and weaker males would be crowded to the wall, and, in 

 many instances, entirely deprived of all conjugal rights, which would be 

 usurped by the larger and stronger animals. 



As a result of these conditions, certain males would obtain possession of 

 several females, and deprivu all other males of access to them. This would 

 be polygamy in the sense used in this paper. The whi-skered seal [hrignathus 



6 This word, although (luestionable. Is the only one known to the writer by which 

 the meaning, indiscriminate intercourse, can be tersely e.xpressed. 

 'The Descent of Man. p. 248. The italics are mine. 



