XX INTRODUCTION 



they may be regarded as vicarious species, unless it is preferred not to 

 recognize any difference between them. As instances I may mention 

 Dipterocarpus indicus and D. turhinatus^ Elceocarpus tuberculatus and 

 jEJ. aristafus. These cases are analogous to the vicarious species on both 

 sides of the Atlantic, such as Cercis SiUquastrum and C canadensis^ Ostrya 

 car]_nnifolia and 0. virginiana. 



There are one or two instances of genera, which are found in Eastern India 

 and tropical Africa, but which have not yet been discovered in the Western 

 Peninsula. The most remarkable instance is Dalliousiea bracteata and 

 africana^ two species so closely allied, that they have been united in the Flora 

 of British India and of Tropical Africa. 



The forester will naturally wish to know to what extent these remarks relate 

 to the more important forest trees. Omitting the trees of the Himalaya, we 

 may single out 60 as being by far the most important among the large number 

 of species here described. Of these sixty, 20 are Western, such as : Shore a 

 rohiista, ChJoroxylon Swietenia^ Dalbergia latifolia^ Pterocarpus Ilarsti- 

 pmm^ 17 are Eastern, such as : Hopea odorata^ Pterocarpus dalhergioides, 

 Pinits Khasia and JDendrocalamvs giganteus^ while 23 belong to both 

 divisions, among them Xylia doldbriformis^ Acacia Catechu, Terminalia 

 Chehula, Lagersfrcemia flos-regince, Tectona grandis and Bambusa 

 arundinacea. 



The preceding remarks must not be misunderstood. Many genera and 

 species are common to both the Westeim and Eastern divisions of India. A 

 comparison of localities similar as regards moisture and elevation will show 

 this abundantly. A very remarkable instance of this is mentioned by Hooker 

 on p. 33 of his late Sketch of the Flora of British India. He compares the 

 Nilgiri flora with that of the cool regions of the far distant Khasi, Manipur, 

 Naga hills and the hills in Northern Burma. Moisture, elevation and soil are 

 similar, but these localities are separated by 14 degrees of latitude and 

 17 degrees of longitude. The following are the most remarkable instances 

 mentioned by him : Rubus, of which 2 species are common to the Nilgiris and 

 to the hills of Eastern India, is a large cosmopolitan genus. Hypericum and 

 Ehamnus belong to the Northern temperate zone, but have representatives in 

 mountainous regions within the tropics, of which Hypericum Hookerianum, H. 

 onysore7ise^ndL nepaulense, Rhamnus virgatus and E. Wightii are found on the 

 Nilgiris. Of Yihurnum, a genus of the temperate and subtropical regions of 

 the Northeim Hemisphere, 15 species are found in India, and 4 of these: 

 F. punctatum, V. coriaceuin, V. odoratissimum smd V. erubescens, are common 

 to the Western and Eastern region (see p. 361). This most interesting com- 

 parison of the Nilgiris and the hills of Eastern India does not invalidate what 

 has been said regarding Eastern and Westeim genera and species. The 

 Nilgiris have no oaks, no pines, no Pyrus, no Hamamelidacem, no Saxi- 

 fragacece^ no Agapetes or Penfapterygium, and many other genera common 

 on the hills of Eastern India, are wanting on the Nilgiris. 



A most interesting and valuable account has lately been pu.blished by 

 Capt. A. T. Grage, IJI.S,, of the vegetation in the Minbii district, which forms 

 part of the dry region of the Irawadi valley in Upper Burma. {Records of 

 the Botanical Survey of India, vol. III. 17.) This district the author 

 divides into three regions :■— -I. The mountainous zone comprising the eastern 

 slopes of the Arakan Yoma and a lower range of hills running parallel to the 

 Yoma. II. A narrow flat alluvial belt 4-5 miles wide fringing the western 

 bank of the Irawadi river. III. The desert zone 20--30 miles wide, comprising 

 the greater portion of the district. In this zone only 60 of the 700 species 

 collected by him were found. The most striking feature in the vegetation of 

 this zone, Capt. Gage states (p. 17), is the preponderance of Beccan and Indo- 

 African species. At first sight this would seem to upset much that has been 

 said regarding Western and Eastern species. On page 130 the author gives 

 a list of the species found in the desert zone according to their geographical 



