5i 
remains. The limestones of the mainland are penetrated by dykes of 
dolerite, and sections are visible showing what have every appearance 
of being interbedded dolerite sheets. From the sections seen at 
Losoa Doudou (Millport Harbour), it is evident that the Boioro lime- 
stones have a thickness of at least 800 feet. 
There is no evidence as to the age of the Boioro beds ; from their 
position they appear prima facie to lie beneath the Port Moresby 
beds, and they have a totally different lithological aspect to that pre- 
sented by the latter. It is possible that the hard leaden-grey Boioro 
limestones may be of a similar nature to the Globergerina limestones of 
the Solomons and New Caledonia. 
4. Purari River Beds. — In the year 1893, a series of blue lime- 
stones and green ( ( glauconitic ) sandstones were met with in the Purari 
River, at 120 miles from the coast, and lying at altitudes reaching up 
to 3,000 feet. 
The Purari River enters the Gulf of Papua by several mouths, in 
East Longitude 145 0 13' and was traversed by the Administrator in a 
steam launch to something like 120 miles, and the traverse was con- 
tinued for four days in a river boat as far as a point called Biroe. From 
the head of the gulf, the Purari wended generally northwards as far as 
S. Latitude 7 ° 54' where it was joined by an important tributary called 
the Aure, flowing southwards from the mountains of the interior. The 
Aure measured from 80 to 100 yards wide, and had a depth from one 
to two fathoms. From the junction the Purari River trended west- 
ward along the foot of a lofty escarpment 3,000 or 4,000 feet in height 
formed of sandstones. The main range, as seen from Biroe, lav about 
15 miles distant, and presented the appearance of great toothed and 
nearly perpendicular peaks. At Bitoe, S. Latitude 6° 54', about one 
degree south of the German frontier, the river had not perceptibly 
diminished in size, but was much broken up by large islands. Below 
the Aure junction, observations were made as to the dimensions of the 
Purari ; the width at the spot selected was 265 yards, the mean depth 
22 feet, and the speed of the current almost 5 miles per hour. Past 
this spot there flowed 64,624,700,000 gallons of fresh water per day, 
or in other words, sufficient to supply 43 gallons of water per day to 
every person of the population of the globe during the year these 
observations were made. The Purari River thus proves to be the 
second largest river in the Possession, being more than one-third, and 
less than one-half, the size of the Fly River, which latter discharges 
180,000,000,000 gallons per diem. To put it in a simple form, and 
to make the significance of these figures more comprehensible, the Fly 
River discharges fresh water enough to supply twice the population of 
the globe with 60 gallons per day. 
