156 J. STANLEY GARDINER. 
studded with relatively large reefs, themselves usually faro. South Male is very similar but 
much smaller. Many of the circumscribing reefs are narrower and without velu. Felidu is 
enclosed by linear reefs or small patches with little velu and narrow passages between. 
Where the passages are few, the lagoon is almost free from reefs, but where numerous 
very patchy. Mulaku taken as a whole is still more enclosed, and the lagoon is more 
open; its shoals are however mostly smaller than in the lagoons of the more northern banks. 
The circumscribing reefs still have linear velu stretching along them, but they do not at 
all approach the ring condition. 
In the western line Ari is intermediate to some extent between Mahlos and North 
Male, having a well-defined rim of large faro to the west and south with a series of 
reef-patches and small faro to the east. A few parts of the lagoon are filled in with small 
reef-patches, but generally the latter is studded with faro or relatively large reefs. North 
and South Nilandu have still numerous passages but are more definitely circumscribed by 
elongated faro than North Male. The north atoll might be placed in the series between 
North and South Male, the south one between the latter and Felidu. Both have open 
lagoons with few but relatively large reefs. 
The series ends in a typical atoll, Kolumadulu, which save for its greater size, being 
26 miles in diameter and covering about 430 square miles, differs in no respect from those 
found elsewhere in the Pacific and Indian Oceans. It has a long linear circumscribing reef 
with only 17 passages, most of which are very narrow. The reef itself is in few places 
more than three-quarters of a mile in width, and, where it is as much, it is either crowned 
with land or has a pool of deep water in the centre. The lagoon is relatively open, a 
circumstance due not in any way to a decrease in the number of shoals, but to the latter 
being of small size, mostly indeed mere patches. Haddumati lastly is very similar, but if 
possible still more perfect in shape. Its reefs generally are, except where covered with land, 
narrow with no trace of velu, and there are only six passages, mostly very small, into the 
lagoon. 
A most important point of difference from north to south hes in the gradual increase 
of the banks in depth, but whether this be correlated with their position or with the 
perfecting of the atoll-form is not quite clear. The small banks, having relatively a greater 
amount of reef around them, would naturally be expected to be shallow, as is indeed the 
case. The large banks admit of a direct comparison, and this shows an irregular increase 
from Tiladumati to Kolumadulu. In that Ari and the two Nilandu are fairly open banks, 
and yet have soundings of 36 to 38 fathoms, and the two Male atolls less depths the 
increase might at first sight seem to be a function of the position. But if Felidu be 
examined, its greatest depth (41 fathoms) is in the south-east horn, which is almost completely 
enclosed by reef, while its greatest depths in the northern more open part do not exceed 
30 fathoms. Generally indeed in examining all the banks it will be seen that the greatest 
depths are towards the centre and in the most enclosed parts of the lagoon. It will then 
be clear that the depth is rather a function of the state of perfection of the atoll-condition 
than due to the position of the banks. Size is undoubtedly a factor of importance, but 
the conditions, which govern the depth, are certainly the same as those which give rise 
to the atoll. 
Another notable variation is found in the extent to which land is distributed on the 
reefs in the centres of the banks. Here again the atoll-condition is probably the determining 
