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of some West African Fishes. 
being an included portion of the body cavity into which there 
still open a number of nephrostomes. These nephrostomes open 
upon a slight groove which will eventually become the dorsal wall 
of the oviduct. 
While searching for the nests of Polypterus I discovered 
the underground nests of Protopterus annecteus and obtained 
a complete series of eggs and larvae. The entrance to the 
burrow is in but a few inches of water, and when the water 
around the mouth of the nest dries up, the parent (who lives in 
the nest with the eggs and larvae) is seen to lash the surface of 
the water with its tail. The larvae are provided with four pairs 
of plumose external gills and a ventral sucker as in Lepidosiren ; 
soon after hatching they attach themselves to the sides of the 
nest by the sucker and hang in a vertical position. The larvae 
hatch in eight days, and leave the nest in twenty days. The 
external features differ from those of the Lepidosiren only in 
unimportant details ; there is in the larva of Protopterus, however, 
an indication of a spiracular cleft. 
I also found the nests of Gymnarchus niloticus. These are 
made in about three feet of water and float on the surface. 
The nests are two feet long and a foot wide, the wall of the 
nest standing several inches out of water, except at one end 
where it is two or three inches below the surface, and leaves an 
entrance to the nest. The eggs measure 10 mm. in diameter; the 
larvae hatch in five days, when they greatly resemble the embryos 
of Selachians. The gill arches are not covered by an operculum 
and bear rows of gill filaments which later become of great length 
and very numerous. The yolk-sac becomes drawn out into a long 
cylindrical bag which is completely absorbed by the time the 
larva leaves the nest. Each nest contains about 1000 eggs. 
The nests of Heterotis niloticus were very abundant. They are 
built on the swamp bottom in two feet of water. They measure 
four feet across, the walls reaching the surface of the water. 
When completed this nest is perfectly round and the bottom is 
quite smooth. The eggs measure 2J mm. in diameter, are quite 
round and bright orange in colour. The larvae soon after hatch- 
ing form a swarm in the centre of the nest and are provided with 
long protruding gill filaments. 
In the same swamps Sarcodaces odoe, Bl., lays its eggs in masses 
of froth on the surface of the water. The eggs measure 3 mm. 
and are transparent. The hatched larvae are provided with con- 
spicuous adhesive organs on the front of the head with which they 
hang to the under side of the surface. 
I also found nests containing eggs which apparently belong 
to Hyperopisus hebe, Lacep., one of the Mormyridae. These nests 
are scooped out from the swamp bottom ; the eggs are attached 
