632 Mr. R. Gurney on Scapholeberis aurita. 
projecting teeth, indicated in fig. 1. There may be from five 
to eight of these teeth, the first (which is the largest) placed 
just at the junction of the transverse and inner longitudinal 
ridges, and the remainder along the latter to a point about 
halfway along the shell. They increase somewhat in size 
from before backwards. 
Fig. 2. 
Now it has been shown by Scourfield that it is by means 
of the modified sete of its flattened shell-margin that 
S. mucronata supports itself from the surface-film, and it 
might be supposed that S. aurita, lacking these sete#, would 
