DESCRIPTIONS OF NEW SPECIES OF LEAIA. By John Mitchell, late Principal of the Technical College and School of Mines, Newcastle, N.S.W. (Plates xli-xliii.) [Read 25th November, 1925.] Introduction. The history of the genus Leaia, as far as Australia is concerned, is a brief one. The first Australian specimens of the genus were found by the writer (1890) in some fragments of chert rock, used to macadamize the main road between Belmont and Charlestown, and hence were not in situ. These specimens were handed to the late R. Etheridge, Jr., for identification, and later were described by him (Proc. Linn. Soc. N.S.W., (2) vii, 1892) under the name of Leaia mitchelli. Subsequently, from a load of the same kind of material referred to above, placed by the roadside at Belmont, Lake Macquarie, for conversion into road metal, the writer had the good luck to discover a number of beautifully preserved fossil insect wings (1898), which proved, and are still proving to possess special scientific value. After much search, the quarries yielding the rocks containing the phyllopods and insect remains were located, and since then many additional fossil examples of Leaia and insects have been gathered, among which quite a number of new types occur. As will appear from the contents of this paper, new species, or varieties, as the case may be, of Leaia, found since the publication of the late Mr. Etheridge's paper descriptive of the first species of that genus from Australia, prove to be so numerous as to make it advisable to extend the history of the genus. An outstanding feature in connection with Leaia in the Newcastle Coal Measures, is the relatively large number of species or varieties found together in the Belmont Beds in a stratum not more than half an inch in thickness. From this layer have been obtained several forms more or less resembling L. leiclyi Lea, and L. mitchelli Eth. Junr., several tricarinate species, one quadricarinate, one unicarinate (?), and a discoidal form; and further, it is to be noted that odd examples are met with in these measures throughout a thickness of some six hundred feet, from the Dirty Coal Seam up to the Belmont Beds; and throughout this same range also, fossil insect remains are in evidence as well as Estheria in considerable variety; these latter it is intended to describe later. The fossil fiora and fauna associated with the Leaia now under discussion go to show that they were dwellers in fresh, quiet, and shallow water; and their end, in the Belmont Beds, was brought about by the sudden drying up of the waters, aided by an invasion over the area of much volcanic dust. This would account for the large number of fossil Leaia now found in the thin layer of rock in the Belmont quarries referred to above. It may be pointed out here that the so-called chert rock of the Belmont quarries, which is met with also in thin
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