On new Bats from the Cameroons. 633 
not have the same habit. It does indeed differ in some 
respects from its relative, being much less active in its move- 
ments, and also it does not always, as Lilljeborg * has already 
pointed out, swim upon its back. In fact its movements are 
somewhat aimless, and it seems likely that this is due to the 
almost total absence of the spinous posterior prolongations of 
the valve, which, like the spines of Decapod zoéas, may 
serve in S. mucronata as directive organs. But it has exactly 
the same habit of swimming on its back suspended by the 
surface-film. If it is examined in this position in the way 
recommended by Scourfield—namely, by brightly illuminating 
the surface of the water, and then focussing a lens upon the 
animal—it can be seen that where it touches the surtace there 
are two rows of minute breaks in the surface-film, between 
which the swimming-legs may be seen moving. ‘These 
breaks have the appearance of elevations, but it is very diffi- 
cult to distinguish an elevation from a depression when of 
such minuteness. I believe that these breaks are made by 
the small teeth upon the inner longitudinal ridge, and that 
they are actually depressions caused by these teeth piercing 
the surface-film. If that is so, we have an interesting case 
of the same end being attained by widely different structures. 
It would be very instructive to know whether in S. micro- 
cephala there is yet a third arrangement for the same purpose. 
These teeth appear also to be used by S. aurita for tempo- 
rary attachment to submerged objects, such as the sides of a 
glass vessel in which it is contained. One other point may 
be alluded to, namely, the colour. In all the specimens of 
S. aurita which I have seen the colour is more or less deep 
orange, though it varies greatly according to Lilljeborg, 
There is no localized distribution of the pigment about the 
ventral surface such as obtains in S. mucronata and has been 
explained as a protective modification. 
LXVI.— Three new Bats from the Cameroons, discovered by 
Mr. G. L. Bates. By OLDFIELD ‘THOMAS. 
Nycteris arge, sp. n. 
Allied to N. thebatca, but with much smaller tragus. 
Size medium. General colour dark brownish above and 
below. Nose-leaf of normal structure, but unusually thickly 
* ‘Cladocera Suecie,’ 1900, p. 164. 
