BOTANICAL GEOGRAPHY. 



395 



In these tracts, hares, partridge, and quail, are of common occur- 

 rence, and are as strictly limited to them, as the plants themselves- 



Another very distinct region is furnished in the Jheels of eastern 

 Bengal. Of these I am only acquainted with the summer vegetation. 

 In winter, a large extent of these inundated lands, when the inun- 

 dations subside, are brought under cultivation. The region 

 is of large extent, extending from some distance to the west of 

 Dacca, to the foot of the mountains lying to the East. The vege- 

 tation of the spots not submerged, agrees exactly as might be ex- 

 pected, with that which characterises humid places in Bengal : viz. 

 Calamus, Pterocarpus, Stravadium, Apluda, and Saccharum. The 

 principal components of the aquatic vegetation, are Oplismenus 

 stagninus, Leersia aristata, Panicum brunonianum. Oryza sativa, 

 O aristata, and O. aristegera, are commonly met with, and form 

 in many instances beds nearly as thick as those of Oplis. stagninus 

 and Vossia procera, which appear to be local. 



Nymphaeaceae abound. The most common species are Nymphaea 

 pubescens, Villarsia indica, and cristata, Potamogeton, Myriophyllum, 

 Cyrilla aquatica, and Utriculariae 2 species, likewise occur. 



The birds are the Cormorant, the jacena cauda alba, Anastomus 

 coromandelianus, Ardea javanica, A. malaccanis, A. purpurea and 

 another large species of Heron ; Ciconia umbellata, C. argala, Ibis 

 melanocephalus, and other wild fowl. 



Fresh water shells abound in numbers, but not in the variety of 

 species ; at least I only obtained 6 or 7 in the course of 10 or 12 

 days, namely a large black muscle, Paludina, Turritella, Succinea, 

 and a large Bulimus common every where in marshy places 

 throughout Bengal. This is confirmatory of the remark by Swain- 

 son in Murrays Geography, as to the small amount of Indian 

 fluviatile shells. 



At equal elevations, moisture is certainly the most powerful 

 agent we know of in the distribution of plants. This is particularly 

 conspicuous in mountainous regions such as Bootan, where a great 

 part of the country is barren, almost to an extreme. 



This is very curious, and just the reverse of what we should be 

 led to expect, since these barren regions occupy the lower tract, 

 that is, from the plains to about 4500, or 5000 ft. This occurs almost 

 without exception. Perhaps however it may be found to be confined 



