THE TABULAE LISTS. 201 



These zones are marked by characteristic changes in the vegetation. 

 In the outer tarai the banks of the great rivers and adjoining depres- 

 sions subject to inundation are clothed with giant grass. On the 

 higher rolling land are stretches of sctl^ forest alternating with tangled 

 jungle — much of it now cleared for cultivation. The Himalayas 

 rise abruptly out of the tarai yAava., and a tangled forest covers their 

 sides up to about 5,000 feet.^ The temperate zone coincides generally 

 with "the oak forest" region, where the undergrowth becomes percep- 

 tibly less rank and dense. The oaks first appear about 4,500 feet, 

 amongst the still luxm-iaut semi-tropical vegetation, as a few strag- 

 gling large-leaved species, which gradually become more numerous 

 towards 5,000 feet. The centre of the temperate zone has a mean 

 temperature of about 50" Faht., that is very much the same as 

 London ; and in December and January frost, and sometimes snow 

 lies all day unthawed in situations with a northern exposure. The 

 Sub-Alpine zone is practically the region of the rhododendron and pine 

 forests. The pines appear about 9,000 feet and soon form open forests, 

 alternating with stretches of rhododendron and dwarf bamboos, which 

 at times form almost impenetrable matted scrub. The limit of trees 

 is 13,000 to 14,000 feet, but in exposed situations it is much lower. 

 Vegetation altogether disajipears at about 15,000 feet, depending on 

 exposm-e and proximity to snow jieaks and glaciers. The line of 

 perpetual snow ranges from about 16,000 to 17,000. 



In regard to horizontal distributioii, Sikhim zoologically is situated 

 on the border-land between the Palsearctic and 

 tio^o^f sTkS'^ ^°''' Oi-iental regions* and, as we have seen, it connects 

 with both these regions, viz., with Patearctic Tibet 

 and with several sections of the Oriental region. Thus its fauna is 

 representative of both these regions — the Palajarctic forms entering from 

 the north in the same way as the Oriental enter the mountains from 

 the south ; but a few Ethiopian forms also occur. As Sikhim stands 

 at the junction of the Indian, Indo-Chinese, and Indo-Malayan sub- 

 regions of the Oriental region, each of these regions is represented in 

 its avifauna. The Oriental forms seem to ascend no higher than about 

 8,000 to 10,000 feet. 



' Shorea robust a, 



' In the upper sub-tropical section, the Urticaria, — figs and nettles are very prominent. 



^ Wallace, following Sclater and other naturalists, divides the surface of the globe, zoologi. 

 cally, into six great regions, viz.. (1) The Palrcarctic, including Europe, Africa, north of the 

 Sahara, and Asia north of the great wall of the Himalayas ; (2) the Ethiopian, comprising 

 the rest of Africa with South Arabia and Madagascar; (3) the Ocjen^a^, consisting of India, 

 Southern China, Burma, Siam, and the Malay Peninsula and adjoining islands of the Archi- 

 pelago ; (4) the Australian, comprising Australia, New Zealand, and the remaining south-eastern 

 islands of the Malay Archipelago, &c. ; (5) the Neartic, and (6) Neotropical, approximately 

 corresponding to North and South America. 



