THE SPIDERS OF EPPING FOREST. 187
etically this is so ; but as this latter denomination has
been almost universally adopted by arachnological
writers I see no pressing necessity for the alteration.
The legs are terminated by two or three curved and
usually pectinated Tarsal Claws. These are almost
always attached to the tarsus itself, but occasionally to
a small supernumerary joint known as the Onychium.
In some species a dense cluster of hairs is found beneath
the extremity of the tarsus, known as a Claw-tuft, and a
similar structure sometimes extends along the inferior
surface of the joint, it being then known as a Scopula.
In some families the metatarsi of the fourth pair of legs
are each furnished with two closely set rows of short
curved bristles, forming a kind of comb. This organ,
known as the Calamistrum is always co-existent with a
supernumerary spinning organ, and by its aid a peculiar
flocculent web is drawn from this spinner and spread
upon the snare. The calamistrum is absent in the adult
male, whose spinners, however, are similar to those of
the female. The relative length of the legs is often of
some importance in classification, and is usually
expressed by a formula. Thus IV., I., II., III., would
indicate that the fourth leg was the longest, the first
coming next in length, and the third the shortest.
When two legs are of equal length the numbers denoting
them are connected by a hyphen. Tibia I., tarsus IV.,
and similar expressions are often used, denoting the
tibia of a leg of the first pair, tarsus of a fourth leg and
so on. The legs are furnished with hairs, and usually
with spines also.
Abdomen. The posterior great division of the body is known
as the abdomen. With the exception of one rare exotic
species it exhibits no distinct segmentation, unless,
indeed, the small Anal Tubercle which is often present
may be regarded as a segment. The abdominal integu-
ment is usually pliant and non-resistant, but occasionally
it becomes more or less coriaceous.
Spinners. Towards, or at the posterior extremity of the
abdomen are several pairs of appendages known as the
spinners. These organs vary in number in different