ON WHALES AND SEALS. 5 



bone and oil. Producing but a single young one at a birth, 

 this huge and harmless mammal will probably disappear unless 

 measures are taken for its preservation. The same may be said 

 of the other whalebone whales which are pursued for profit, 

 and of the dugong and manatee, the oil, skin and skeletons 

 of which are of value. The huge Pacific grey whale {Rhachi- 

 nectes glaucus) of the lagoons of the Californian coast has, indeed, 

 been entirely destroyed by man. 



The effect of the slaughter of hundreds of the ca'ing whale 

 (Globiocephalus melas) is not so clear, but the xiphoid whales 

 captured in the north seas for their oil are in greater danger. In 

 no species has the inability of recuperation from constant attacks 

 been better illustrated than in the sperm-whale, the numbers 

 of which have been seriously diminished within recent times. 



The effect of man's keen pursuit is also well shown in the 

 seals, which are now so scarce on many parts of our own shores. 

 Only in the more remote regions (as in the sound of Harris) 

 are they to be met with in considerable numbers. Yet here 

 and there the absence of interference and the presence of a 

 favourite food may occasionally lead to their appearance in 

 larger numbers, as at the mouth of the Tay. Man's effective 

 influence on them in their headquarters in the Arctic seas is 

 unchallenged, since their breeding places are on land. 



These large air-breathing marine forms, therefore, occupy a 

 special position, and make a contrast with the majority of the 

 types we have now to consider. 



Of great importance in connection with the subsequent 

 groups is the plenitude and variety of marine plants. Familiar 

 forms of these are the green, red and olive weeds of the rocky 

 shores and tidal pools, and the grass-wrack of the muddy flats. 

 In certain places indeed the perennial growth of the olive 

 weeds was formerly of at least as much importance to the 

 inhabitants as their grain-crops. The immense Sargasso-sea 

 off the Azores, and the smaller ones in the Atlantic, again, 

 have long been a source of interest and wonder. Various 

 naturalists further have noted the discoloration of the sea 

 from the abundance of microscopic plants, have observed the 

 occurrence of vast masses of diatoms in the south Pacific, and 



