Daintree. — On the Structure of certain Igneous Rochs. 459 



patches appear to be cavities filled with the fine-grained basaltic portions of the 

 rock. 



No. IX. — (Snowy Peak Range.) Similar to Ko. 2076. 



No. 410. — (Haurata District.) This rock differs from those classed under 

 this head, as orthoclase and plagioclase are both present. The brown mineral 

 is probably augite ; the colours, however, as seen in polarized light are far less 

 brilliant than usual. 



The base contains an immense number of microlites, and exhibits well the 

 " fluidal" structure. Under a \ inch objective the microlites appear of a clear 

 yellowish brown j they are probably augite. 



No. 218. — (Flagstaff Hill Basin.) This specimen consists of a fine- 

 grained matrix composed of small grains and crystals of augite, plagioclase, 

 and magnetite, in which larger crystals of olivine are imbedded. 



No. 39S.— (Haurata District.) Contains the same minerals as No. 218, 

 together with slender acicular crystals of apatite. 



The olivine has been much decomposed, and hydrous ferric oxide in some 

 cases only remains. 



No. 204. — (Acheron Section.) A weathered specimen. The felspar is 



very much altered j some appears to be orthoclase. There are many long 



prisms of apatite, and the small hexagonal crystals are the transverse sections 



of the prisms. • 



Trachytic Rochs. 



No. 308. — (Mount Misery.) Contains crystals of quartz and orthoclase 

 in a compact felsitic base. 



No. 358. — (Snowy Peak Range.) A similar rock of greenish colour. In 

 addition to the quartz and felspar it contains a few garnets. 



No. 359. — (Snowy Peah Range.) This appears to be the same as No. 358 

 in a fragmental condition, produced probably by the crushing action of the 

 mass when in motion at the time of eruption. 



No. 366. — (Snowy Peak Range.) This rock contains crystals of quartz 

 and orthoclase, a few grains of garnet, and a little brown mica. It exhibits 

 the fluidal structure very well, and, as part of the base is a structureless glass, 

 it may be regarded as intermediate between felsite and pitchstone. 



Granitic. 



No. 348. — (Snowy Peak Range.) Consists of orthoclase, a considerable 

 quantity of plagioclase (probably oligoclase), and a little silvery mica. 



There is a yellowish mineral with a fibrous radial structure seen both in 

 the specimen and section. It is evidently a secondary formation, filling spaces 

 between the constituents. It is probably prehnite. 



Pitchstones. 



No. 349. — (Snowy Peak Range.) Contains crystals and crystalline grains 



