traced as far north as Yamèthin and is very probably continuous with a broad belt of the same rock in the Kyauksè district. A different kind of granite containing the mineral tourmaline has been injected into the schists of the Tawngpeng system in the Ruby Mines sub-division and is also found associated with the Mergui beds of Tenasserim.
The Tawngpeng rocks formed a continuous floor on which the fossiliferous sediments of the Palaeozoic ocean were deposited. There is some interesting evidence by which it seems probable that the Tawngpeng rocks in the Shan States area projected here and there above the surface of this ocean in the form of islands, for some of the sediments of the Palaeozoic ocean thin out in a remarkable way as they approach these islands, and frequently overlap older sediments below. An example of one of these islands is the mountain mass of Loi Leng.
The records which follow thrill one with their clearness and their absorbing interest. They are scored on rocks which contain a rich fauna generally similar to that found in the rocks of North Wales and on that account termed the Ordovician system. The largest exposure of these rocks is to be seen about 11 or 12 miles east of Mandalay. Their fauna includes specimens of the stalked, bud-like, extinct animals known as cystids, many species of brachiopods—bivalve shell-fish of which one shell covers the back and the other the belly—including more than one identical with European forms, and many remains of the curious, extinct, primitive crustaceans known as trilobites. The earlier sediments of this system are homogeneous over wide areas in the Shan States, and indicate an open sea of uniform but no great depth, with a coast-line somewhere to the west. The later deposits are crowded with shell fragments and the detached eyes of trilobites, and were evidently laid down in a sea teeming with life. Perhaps the most interesting point about the Burmese Ordovician, however, is the relationship of its fauna to that of other
