iiY H. I. JENSEN. 585" 



There are numerous other similar deposits in the vicinity of 

 Bugaldi on other hills and also in some of the valleys. 



On Paddy McCulloch Mountain near Yarragrin Springs, a 

 similar deposit occurs at about the same altitude in similar 

 associations. 



Besides tuffs, petrified wood, petrified leaves and twigs, opal, 

 silicified breccia and chalcedon}'- are commonly associated with 

 these deposits. From the associations we may judge that the 

 diatomaceous earth deposits were formed in hot lakes and siliceous- 

 hot springs situated either in the craters or close to them. 



Mr. E. J. Goddard has kindly examined the diatomaceous- 

 earths collected by me (a) at Wandiallabah Creek, (b) at Chalk 

 Mountain, (c) at Paddy McCulloch, and finds that the material 

 from each locality consists mainly of the common variety, 

 Melosira. Rewrites: — " The earth collected from the localit}' 

 of Chalk Mountain consists of the frustules of several species 

 of Melosira allied to Melosira crenulata and M. granulata, both 

 of which are well-marked European freshwater forms, and no 

 doubt occur among our, so far poorly examined, diatomaceous- 

 flora at the present day. The genus Melosira is the characteristic 

 organism of diatomaceous earths in New South Wales. In the 

 diatomaceous earth deposit of Chalk Mountain the forms present 

 are much larger than those from Wandiallabah Creek. Spicules 

 of the freshwater sponge, Spongilla, are also present, but are by 

 no meixns abundant as in the Wandiallabah Creek deposit." 



Addendum.— In the trachyte tuffs of Gowang I have met with 

 leaves or fragments of leaves belonging to the species Cinna- 

 momum Leichhardtii Ettingsh., Endiandra prcepuhens Deane, 

 Anojyterus Pittmani Deane, and Cryptocarya prwobovata Deane. 



(b) (9;x(?.-- Numerous seams of common opal, chalcedony, and 

 allied forms of silica occur in the trachytes and associated tuffs. 

 They are generally accompanied by silicified breccias, and petrified 

 wood; and are probably the result of hot-spring action. I believe 

 that there is every likelihood of good opal being found in some 



