BY J. BRAZIER, C.M.Z.S. 235 



On some Mesozoic Fossils from Central Australia. 



By the Rev. J. E. Tenison- Woods, F.G.S., &c. 



With Two Plates. 



The fossils described and figured in this paper were obtained by 



Mr. Gilliatt, one of the surveyors in the Mining Department. 



They were found in sinking a well on Mount Stewart Run, which 



is situated on the Grey Ranges. The fossiliferous bed was struck 



at a depth of 90 feet. The remains comprise many specimens of 



Avicula, some Grypheoe, a Trigonia. Belemnite, Pecten, Ostrea, 



Pinna, Cyprina, Mytilus, and many broken fragments. The only 



species which can be determined, are of Avicula, Pecten, Trigonia 



i.nd Belemnites, the rest being too imperfect. 



The sand is of a greyish green color, with numerous blackish 

 grains. In places it is finely levigated, so as to preserve impressions 

 of the faintest markings on the shells. Some portions are a coarse 

 grey green sand, easily powdered. Under the microscope, this 

 sand is seen to be composed of angular fragments of crystals, with 

 small portions of shelly matter. There were very few rounded grains 

 ind none polished. When treated with hydrochloric acid, there 

 vas only a slight effervescence, confined I suppose to the fragments 

 of shelly matter. I could not dectect any Foraminifera. Some of 

 ■he fragments of crystals were dark black or green, some opaque 

 vhite, and some transparent. There were also a few brown opaque 

 grains. The transparent grains seen in polarized light, all showed 

 )ands of color and some twin crystals and triclinic felspar. The 

 "arge green crystals were dark and opaque ; some of the smaller 

 lark grains had almost a metallic lustre. From the absence of 

 my glassy particles, as well as there being so little marks of ferric 

 )xides, we may conclude that this sand was derived from the 

 weathering of some of the ancient granite rocks, and not from 

 volcanic or trap rocks. There is a general external resemblance in 

 the rock to the greensands of Britain and France, but the 

 resemblance is merely external. There is no trace of the glanconitic 



