1886.] MR. BOURNE ON THE FAUNA OF DIEGO GARCIA. 331 
shed her spawn between her ventral fins, which were clasped 
tight together, and, when full, swam to the nest, and, turning on her 
back, deposited the spawn in it; this occurred several times, the male 
cach time putting the spawn in its proper place and covering it with 
froth. As soon as the female had dropped all her spawn the male 
took entire possession of the nest and would not let his mate go 
anywhere near it, and treated her so badly that I had to place her 
in another tank to save her life. Unfortunately the spawn was not 
good, only a few eggs hatching, and the young fishes dying soon 
afterwards. 
“T have bred great quantities of the little Callichthys punctatus 
from the Amazons, but they never made the slightest attempt at 
making a nest, always depositing their spawn all over the tank, 
and even on the floating thermometer kept in it. 
“Yours faithfully, 
TAM: Vreaw.” 
The following papers were read :— 
1. General Observations on the Fauna of Diego Garcia, 
Chages Group. By Guiiperr C. Bourne, B.A., New 
College, Oxford. 
[Received May 15, 1886.] 
Diego Garcia is the southernmost atoll of the Chagos group in 
the Indian Ocean, lying in S. lat. 7° 13’, and E. long. 72° 23’. It 
is of irregular shape, 13 miles long and 6 miles wide, consisting of 
a strip of land of an average breadth of a third of a mile, which 
nearly encircles the lagoon. The opening lies to the N.W., and is 
divided by three small islets into four channels, the largest of which is 
more than a mile wide, and deep enough to allow the largest ships 
to enter the lagoon. The formation is wholly of coral, aud the land 
consists in different localities of sand, accumulated coral-boulders, and 
sand-rock or shingle-rock. It nowhere rises toa greater height 
than the waves have been able to accumulate fragments of coral, 
except in some places, where sand-dunes have been piled up by the 
wind to a height of 25 or 30 ft. above high-water level. As is usual 
in coral-formations, a reef some 60 yards broad encircles the shores ; 
this reef is nearly flat, is composed of a compact finely stratified 
coral-limestone, and is just left bare at the very lowest spring- 
tides. Growing coral is only found on the outer edge of the reef, 
but in some parts the Aleyonarian Heliopore and Tubipore are 
found in large numbers on its surface. Many Holothurians, 
Echinids, Ophiurids, and Sponges are to be found on the flat surface 
of the reef between the tide-marks, and large Tridacne are imbedded 
in it, showing the brilliant edges of their mantles above the rock. 
The naturalist who wades over the reef at low water will be abun- 
dantly rewarded in his search for Mollusca of all kinds, chiefly of 
the genera Cassis, Oliva, Turbo, Nerita, Aporrhais, Aplysia, and 
pis 
