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LiohenB are less frequent than one would expect in such open foreste, and only in more 

 favourable Bituatious are they really conspicuous.* Mosses and scale- mosses are rare, and so 

 are during the hot season the fungi, of which only a few Poli/pori are seen. Alyue are also 

 scarce, at least in number of species ; for what reason I do not understand. 



Epiphytical plants are represented .although in modest numbers ohiefly Dendrohia and 

 Snccolubia. Ferns, terrestriod and ephiphytical, are here to be found in widely distributed 

 forms, but in very small numbers. Those mostly seen are Adiantum lunulatum and rhiifo-, 

 phoriim, Niphoholus adnascens and Plat i/cerium. 



These forests, and indeed, all forests of the Prome district, require further careful examin- 

 ation at a more favourable season, and, no doubt, will repay a botanist richly for liis labours. 



The calcareous sandstone is greatly subject to deoompostion and, to all appearance, was 

 still more so at a time when the rain-fall in the Prome district has been greater. The decom- 

 posed rock closely resembles the permeable silicious sandstone not only in its chemical but 

 also in its physical qualities. It is a more coarse-grained smoke-grey highly permeable sand- 

 stone and supports forests almost identical with the upper mixed forests of the higher crests of 

 the Yomah itself. I strongly suspect, that the greater part of the main range, or the axis, of 

 the Yomah is composed of decomposed calcareous sandstone ; at least the samples I collected 

 in the several crossings of the Yomah, South of the Prome district, do not in the least 

 differ from the decomposed sandstone of the Kambala layers. I am supported in my suppoT 

 eiton by the fact, that there exist large tracts of myinwa (a bamboo characteristic of calcareous 

 sandstone and laterite) in the drier upper mixed forests. Sucli metamorphoses in the 

 character of forests cannot surprise, if we carefully bring into account the amount of rain-fall 

 and perfect drainage : both will suppress dry stunted forests, and call into existence lofty 

 grown upper mixed forests as soon as decomposition has removed the injurious lime. Water 

 has the property of absorbing a certain proportion of carbonic acid, rain takes up more 

 or less carbonic acid,t it dissolves tlie lime of the calcareous sandstone and carries 

 it away in the form of a bicarbonate. We can, therefore, well understand, why the highest 

 and steepest regions of the Prome Yomah (wh^e complete drainage is the rule) should have 

 been first metamorphosed. It is easy to trace (for example in ascending the Swa-passes) 

 the gradual transition from dry forests into upper-mixed forests according to the degree of 

 decomposition of the calcareous sandstone rocks. It is here that we find Peniacme Siamenis 

 (a most characteristic tree of the Prome district) still growing in the midst of the true upper- 

 mixed forests on the main range itself. 



B. S/ia forests. The principal tree here is, as the name given to these forests indicates, the 

 Sha-tree (Acacia catechu). This tree, although it also occurs sparingly in the Irrawaddi zone, 

 becomes here a conspicuous feature, in the same way as Eng, teak and similar trees do in other 

 parts of Pegu. Along with sha, a small number of trees a curious mixture of open and mixed- 

 forests species occur here, along with a few trees, which are peculiar to the Prome zone. 



C. Upper dry forests. I have separated these forests on the supposition that we 

 might be able to give them a more fixed and peculiar character preparatory to an explo- 

 ration of those which occupy the highest crests of the Yomah main range towards 

 Kyouk pyoo toung and Bhambway beng Sakhan. For the present my remarks refer only 

 to those which grow on the Kambala range and along the Yomah crest from this hill to 

 Yan choung, ranging from about 2500 to 3000 feet elevation. These forests may best be 

 designated as crooked and low upper-mixed forests, with an admixture of dry-forest trees, 

 containing certain temperate forms, like Vaccinium, Hcracleum, Hymenopogon, Didymocarpus, 

 etc., indicative of the influence of elevation. The average height of trees is here reduced to 

 a minimum, viz. from 10 to 30 feet, and the trees are scattered and crooked like those in an 

 Eng-forest. Their aspect is peculiar in the extreme. This strange growth of trees is not 

 attributable to elevation, but to two powerful agencies, viz. the dry winds and the dry climate 

 generally (they are situated in and near the Prome zone), the influence of which is increased 

 by the second agency, viz. the presence of lime in the sandstone. The section of Kambala 

 toung under 2, No. 3, gives a good idea of the position these forests occupy with reference 

 to the surrounding forests. Besides the unfavourable conditions already named, to which 

 these forests are subjected, must also be added their exposed situation and solar radiation. 

 Jungle-fires occur here regularly, burning up not only the scanty dried up vegetation, but also 

 running up the short stems of the little trees, and often consuming the shrivelled up mosses 

 and grasses that grow on them. 



A tree that is seldom seen in Southern Pegu, but which becomes frequent in the Prome 

 zone, is Uiptnfje arborea, and this tree becomes here a conspicuous and principal constituent 

 of these forests. With it grow a number of others, nearly all denizens also of the upper-mixed 

 forests, such as Sterculia dllosa, and colorata, Orema elasiica, Gardenia suavis, and scssiliflora 



These are nearly all crustaccous species, the foliaceous and shrubby species seem to be more hygrophilous. 

 t Jungle-fires, which play such a conspicuous role in excessive tropical climates, form another source of 

 supply of carbonic acid to the atmosphere (see Schleiden, Lehrbuch der Botanik, II. p. 460, 3rd Edit.). 



