EXHIBITS, 



81 



ISew Guinea, especially when the specimens are supplied by so care- 

 ful a collector as Dr. MacGregor, who notes both the heights, posi- 

 tions, and general contour of the country. From his remarks on 

 Port Moresby Hills, one must believe that a considerable period of 

 deundation has lowered their peaks to the present height, and there- 

 by caused their sides to be covered with the soil and small stones 

 which Dr. MacGregor mentions. 



Having been requested so to do by the Secretary of the Royal 

 Society, 1 havf 1 ventured to name the five specimens received, 

 although my opinions do not quite coincide with Dr. MacGregor's 

 views on the subject. 



1. Appears to be a weathering felsitic rock, such as would 

 occur in dykes running through the rock- 5 , and hence very likely to 

 form the summit of spurs as mentioned by Dr. MacGregor. Pieces 

 of rock taken directly from the surface are generally a good deal 

 altered in appearance and composition, owing to weathering, nor is 

 the specimen in question an exception to this rule, but it is still 

 sufficiently fresh to see the compact structure and the irregular 

 cleavage which would be so different in a sandstone. 



2. Crystalline limestone. — I am not incline 1 to consider the 

 outside markings as organic remains, but rather a form of weather- 

 ing, determined by such portions of the rock having been found in 

 concentric or elliptical lines around a central nucleus. 



3. A variety of quartz between flint and chalcedony. 



4. Limestone, containing two or three bands, harder but of the 

 same composition, and which have, therefore, by their slightly 

 greater resistance, caused the grooving so common on the outer 

 surface of weathering limestcne. 



5. A peculiarly soft white form of carbonate of lime, to which 

 I can only give the name of soft chalk. 



