BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
140 
islands plainly indicates their former connection with the Australian 
continent. 
It may not be out of place to examine now what light the hydrog- 
raphy of Queensland throws upon the subject of the extension of the 
rocks of the mainland to the outer edge of the Great Barrier Reof. То 
elucidate this point I have prepared a series of sections taken from the 
Admiralty Charts, extending from Moreton Bay to New Guinea (Plates 
XXIL, XXIV, XXXVII. to XLI.). 
The continental plateau off the east coast of Australia is a compara- 
tively narrow shelf, varying in width north of Sydney between fifteen 
and thirty miles, which is the distance at which we find the 100 
fathom line, and where the slope becomes most abrupt, depths of 1,500 
to ove: 2,000 fathoms are reached within short distances. The con- 
tinental plateau widens somewhat to the east of the Capricorn Channel 
(Plate XXXVII. Fig. 6), where it attains a width (its greatest width) 
of nearly 150 miles. "The outer edge then runs in a westerly direction, 
gradually coming nearer the mainland (Plate XXXVIII.), to Flinders 
Pass, whero it is less than forty miles distant from the mainland. 
The outer edge of the Barrier Reef there takes a more northerly direc- 
tion, gradually approaching still more the continental shore, and in 
some places not being more than twelve to fifteen miles from it (Plate 
XXXIX., Plate XL. Figs. 18-22); until somewhat south of Cape 
Grenville, the outer edge of the Great Barrier Reef runs due north and 
expands into the wide continental platform, from 100 to 110 miles, 
which unites the Australian continent with New Guinea (Plate XL. 
Figs. 23-26, Plate XLI.). 
An inspection of the charts and of the sections cannot fail to show 
that the piteh of the narrow continental shelf off the east shore of 
Australia south of Sandy Cape (Breaksea Spit) is much steeper than 
the sea slope of the continental shelf north of it. With tho ex- 
ception of a short distance parallel to the outer edge of the Great 
Barrier Reef and extending from Lark Pass to off Cape Melville, the 
1,000 fathom line is close to the 100 fathom line south of Breaksea 
Spit to well beyond Sydney; while north of Sandy Cape, with the 
exception named above, the 1,000 fathom line forms a great loop to 
the eastward, and is often 250 miles distant from the 100 fathom 
line. So that, in the very region where the Great Barrier Reef 
extends, the continental slope does not compare in steepness to the 
pitch which characterizes it in the non-coralliferous belt to the south 
of Frazer Island. (Compare the different figures of Plate XXXVII.) 
