British species of Scoparia. 511 
not always decide which the specimen before me really 
was. I measured from the base of the clasp to the end 
of its lateral spine, and also the total length of the clasp. 
The result comes out that in ten specimens measured, 
the length from the base to the end of the spine shows 
0°87, 0°90, 0:93, 0°93, 0°93, 0°96, 0°96, 0:96, 0°99, 1:05 mm. 
The total lengths are 1:23, 1-24, 1:26, 1:29, 1°30, 1°35, 1°35, 
1:37, 141,147 mm. These figures show that, though the 
smallest are atomalis and the larger wmbiqualis, there is 
no point at which a line can be drawn to separate them 
as of different sizes, since as a matter of fact the two 
series overlap. 
Cembrae (figs. 24-27) may be taken as a type of the 
root-feeders. The clasps have the basi-ventral thicker 
portion large, and the hook or spine in which it ends is 
two-thirds the length of the side of the clasp from the 
base. It is strong and curved well away from the clasp, 
so that its point is in a line nearly transverse to the 
length of the clasp. 
The dorsal armature consists of an uncus, which may 
be perhaps more easily described by likening it to the toe, 
or rather the front three-quarters of a slipper, but with sole 
and upper in one continuous piece. The sole is on the 
dorsal aspect, the sides are narrow, the apex is prolonged 
to a point, and the two sides meet about two-fifths of the 
total length from the point, the surface has various long 
hairs. In the base of the uncus is hinged a piece that 
must be called the tenth sternite. When closed against the 
uncus it is of about the same length. It is a straight 
piece tapering to a curved point, and basally divides into 
two branches widely separated, and it is by the ends of 
these that it is hinged to the base of the uncus. The 
arch formed by these two branches below and the cavity 
of the “slipper” above give space to the anus. 
The aedoeagus is broad and short, 1 mm. long, or 
perhaps less, as a terminal ring seems to be possibly 
everted membrane, and nearly 0°3 mm. wide. It contains 
two groups of cornuti. In one of these the separate 
spines are so much soldered together that the mass 
might almost be regarded as one spine. In the other 
they are closely connected, but are partially separate, 
the largest one about 0°4 mm. long. 
It is to be noted that the uncus is soft membrane 
carrying hairs, and is easily deformed in preparation and 
