2 
INTRODUCTION. 
prevailing forms being oval, cordate, and quadrilateral. The anterior region, where the eyes 
are situated, is frequently elevated, and is sometimes tuberculated. The covering of the 
inferior portion of the cephalo-thorax, or sternum, likewise consisting of a coriaceous plate, is 
oval, circular, or cordate. It is scalloped on the lateral margins, and often presents small 
eminences opposite to the articulation of the legs. Both these parts are densely clothed with 
hairs in some species, but in others they are almost entirely without hairs, smooth, and 
glossy. 
All spiders at present known have two, six, or eight smooth eyes, which vary much in 
size and relative position, supplying characters of great importance in the systematic arrange¬ 
ment of species. 
The falces, inserted immediately under the anterior margin of the cephalo-thorax, though 
modified in form, are, for the most part, subconical; and have usually at the extremity of 
their inner surface a longitudinal groove provided with sharp teeth on the sides, which receives 
the fang when in a state of repose. The fang is very hard, curved, acute, and has a small 
fissure near the point, which emits a colourless fluid secreted by a gland. These instruments 
are either glabrous, or covered more or less with hairs, and are sometimes armed with sharp, 
corneous points, particularly at the extremity, near the insertion of the fang. 
Spiders belonging to the family Mygalidce have the falces articulated horizontally, their 
movement being vertical; the falces of those included in the other families being articulated 
vertically, or on an inclined plane, and their principal movement lateral, with the exception of 
a few species whole falces are united. 
The maxillae and the sternal lip are directed forwards, or inclined downwards in all 
spiders. The former are hairy at the extremity, which is round, obliquely truncated, or 
pointed. Their configuration and their position in relation to the sternal lip, together with 
the form of the latter, furnish excellent generic characters. 
Connected with the maxillae are the palpi, which project on each side of the falces. They 
consist of five joints supplied with hairs and spines, and are, for the most part, terminated by 
a curved, pectinated claw in female spiders. The first, or axillary joint, is short; the second, 
or humeral joint, is long; the third, or cubital joint, is short; the fourth, or radial joint, which 
is rather long in the females, is usually short in the males, and, in the latter sex, is frequently 
provided with one or more corneous apophyses; the fifth, or digital joint, varies in length; 
but in the males it is commonly short, oval, and dilated, having the sexual or palpal organs 
attached within and partially concealed by a cavity on its under side. These latter organs, 
composed of soft, membraneous, vesicular parts, susceptible of tumefaction, exhibiting on their 
external surface, or at their extremity, various curved, corneous processes, are complicated in 
structure and greatly diversified in form, indicating by their complete development a state of 
maturity. 
Much variety is observable in the figure of the sternal lip, which, as its name implies, is 
connected with the sternum; the prevailing forms are oval, semicircular, quadrilateral, and 
triangular. In the greater number of spiders this part is glabrous. Between the sternal 
lip and falces the palate is situated, whose hairy extremity alone is visible in its natural 
position. 
The legs, disposed round the cephalo-thorax, are composed of a haunch of one joint; a 
thigh and a shank, each formed of two joints ; and a foot, also divided into two joints ; except 
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