12 



HISTORICAL AND GEOGRAPHICAL 



Lastly, of about 200 species of Butterflies occurring in the island, some- 

 thing like three-fourths are confined to it, while these insects as a whole 

 present certain peculiarities of shape, size, and colour, which readily dis- 

 tinguish them from their allies in other parts of the Malay Archipelago. 



MARINE FAUNAS. 



The sea, like the land, is tenanted by forms of life in every part, and 

 these are specially adapted for existence under the peculiar conditions 

 imposed by their surroundings. Not only shallow water, but also the 

 greatest depths ever reached by the dredge and trawl have yielded a rich 

 harvest of interesting creatures representing almost all classes of animals from 

 fishes downwards. But the distribution of marine animals is not governed 

 by the same principles as that of terrestrial forms, and hence the division 

 of the various seas and oceans into regions and sub-regions cannot be so 

 definite. 



The most satisfactory, and therefore the usual method of grouping 

 marine organisms is that founded on the depth of the water they inhabit. 

 Three areas may be distinguished, namely, (1) the Littoral, embracing all 

 the region from high-water mark down to about 40 fathoms; (2) the 

 Pelagic, including the surface of the open ocean ; and (3) the Abyssal, or 

 deep-sea area. The first of these is characterised by a rich and varied 

 fauna, and may be further divided into (a) the shore; (b) the true 

 littoral zone, exposed only at low tide; (c) the Laminarian zone, extend- 

 ing to a depth of 15 fathoms; and (d) the Coralline zone, extending from 

 15 to 40 fathoms. The Pelagic area likewise possesses a great variety of 

 animal forms, and these are of two kinds, namely, those which drift (known 

 collectively as Plankton), and those which swim actively (called Nekton). 

 The physical conditions of the ocean abyss are (1) complete absence of 

 sunlight, direct or diffused, with a compensating production of phos- 

 phorescence by the inhabitants themselves ; (2) a low and uniform tempera- 

 ture; (3) enormous pressure, amounting at some depths to 2J tons per 

 square inch ; (4) absence of plant life, necessitating purely carnivorous 

 habits on the part of the fauna ; and (5) perfect stillness of the water. 

 These very peculiar conditions have led to the development of the most 

 extraordinary forms, especially in fishes, which are known to exist at a 

 depth of 2900 fathoms. 



Numerous attempts have been made to construct zoological regions for 



marine forms. Thus the conchologist, Woodward, in 1856, proposed no 

 fewer than 18 marine provinces for Mollusca; Fischer, in his Manuel de 

 Conchyliologie (1887), adopts Woodward's scheme and reproduces his map. 

 Again, Giinther, in his well-known Introduction to the Study of Fishes 

 (1880), proposes the following areas for showing the distribution of Shore 

 Fishes : — 



I. The Arctic Ocean. 



II. The Northern Temperate Zone. 



A. The Temperate North Atlantic. 



1. The British district. 



2. The Mediterranean district. 



3. The North American district. 



B. The Temperate North Pacific. 



1. The Kamschatkan district. 



2. The Japanese district. 



3. The Calif ornian district. 



III. The Equatorial Zone. 



A. The Tropical Atlantic. 



B. The Tropical Indo-Pacific. 



C. The Pacific Coast of Tropical America. 



1. The Central American district. 



2. The Galapagos district. 



3. The Peruvian district. 



IV. The Southern Temperate Zone. 



1. The Cape of Good Hope district. 



2. The South Australian district. 



3. The Chilian district. 



4. The Patagonian district. 



In 1896 Dr A. E. Ortmann published a useful little treatise under the 

 title, Grundziige der marinen Tier geographic In this work, which is based 

 on the study of Decapod Crustaceans, he divides the oceans into the several 

 areas shown on Plate 2, where the reader will find an adaptation of the 

 Map given by Ortmann. 



Lastly, on the same Plate is shown the scheme of marine areas proposed 

 by P. L. Sclater for Mammals in 1897, and afterwards published in the 

 volume on The Geography of Mammals (1899). 



