The Common Spiders of the United StatesEmerton, J. H. (James Henry)
Science
The Common Spiders of the United States
Emerton, J. H. (James Henry)
Spiders -- United States
The Drassidæ, like the Lycosidæ (p. 67), are ground spiders, though some
genera, like Anyphæna (p. 12) and Clubiona (p. 15), are equally common
in summer on bushes. They make nests in the form of a bag or flattened
tube, but no cobwebs for catching insects, and are commonly found
running about among dead leaves and short grass and sometimes even on
bare ground and sand. In form they are usually two or three times as
long as they are wide, like the Lycosidæ (p. 67), but more often
flattened on the back. The legs differ but little in length, and the
first and second pairs are directed forward, the third and fourth
backward. Their hairs and spines are short, giving them a smooth,
velvet-like appearance. The feet have two claws, with a brush of
flattened hairs under them, like the Thomisidæ and Attidæ (p. 41), but
unlike the Lycosidæ (p. 67), which have three claws. The mandibles are
large and strong and are together as wide as the head. The eyes are all
about the same size and arranged in two rows of about the same length
and not far apart, but between different species there are slight
differences in their arrangement. The colors are usually dull gray,
brown, and black, with few markings or none. A few species are very
brightly marked, as in Micaria (p. 9) and Pœcilochroa (p. 4).
There are three groups among the Drassidæ:
1. Prosthesima, Gnaphosa, Pœcilochroa, Pythonissa, and Drassus, which
are generally dark in color and flattened above, with the cephalothorax
narrow in front and the eyes covering about half the width of the head
and differing in their relative positions among the different genera.
The labium is long and the maxillæ slightly widened at the end, or with
the outer corners rounded off and sometimes a crease or depression in
the middle. The joints of the first legs are sometimes thickened in the
middle. The lower spinnerets are longer than the others and flat on the
end.
2. Micaria, Geotrecha, Phrurolithus, Agrœca, and Anyphæna, in which
the body is less flattened, the legs longer, and the movements quicker.
The colors are lighter and more varied. The labium is short and the
maxillæ with straight sides.
3. Clubiona, Chiracanthium, and Trachelas, in which the colors are plain
and light, the eyes spread over more than half the front of the head and
close to its front edge. The labium is as long as it is in Drassus, but
contracted at the base. The maxillæ are narrow in the middle and flat
and wide at the ends.
[Illustration: FIGS. 3, 4, 5. Gnaphosa conspersa.--4, female enlarged
four times. 3, the eyes seen from in front. 5, the maxillæ, labium, and
ends of the mandibles from below.]
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account