126 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
to as “sternal cones,’ or simply “cones” (s.co). The labium (lab) and 
maxille (mx) are also shown in Fig. 92. 
VII. 
The parts of the abdomen referred to in description are as follows: 
The dorsum (Fig. 98, do) is the rounded top of the back, of which the 
nae anterior part is called the “base” (ba), and the posterior the 
“apex” (ap). The “folium” (fol) is a leaflike figure which usually 
occupies one-third or more of the middle part, extending longitudinally 
from base to apex. The median line (mn) of the dorsum often has a 
deeper shade of color than the edges of the folium. The blackish “ pits,” 
or round dark spots (pt), symmetrically arranged in pairs on each side of 
the median line of the folium, indicate points of attachment for internal 
muscles. The venter 
(vn, Fig. 94) is the part 
lying between the epi- 
gynum (ep) and gills (gi) 
and the spinnerets (sp) ; 
pits or dimples may also 
be seen on the venter 
symmetrically arranged 
as on the dorsum, ‘The 
median ventral band is 
usually bordered by a 
4 * AppoMEN AND Parts. 
Fic. 93. Dorsal view; pd, pedicle uniting to cephalothorax; ba, base or strip of lighter color 
ar on. dom coos enn a a oe He aa a ee 
mn, median line of dorsum. Fia. 94. Side view; vn, venter; ep, epi- When the abdomen is 
gynum ; gi, breathing gills; other references as above. thickened at the apex, 
the space between the dorsal and ventral apex is known as the apical 
wall of the abdomen. On either side or shoulder of the dorsal base some 
species have conical prominences known as dorsal cones or tubercles (d.co). 
These are sometimes placed at several other points, usually along the mar- 
gin of the dorsum. In some species these are hard and spinous. 
The exterior parts of the epigynum referred to in the description are 
illustrated at Figs. 95, 96. The atriolum vulve, or vulval porch, is a 
vaulted porch or hood that curves over the genital opening, in 
front of which (anterior) it is located. It is usually chitinous, 
and covered at the base with hairs. The middle part in many 
species is prolonged into a shaft or scapus atrioli, which is sometimes a 
mere flap, and again is much lengthened. Sometimes it is smooth, some- 
times wrinkled or rugose, often with a row of stout hairs thereon. Fre- 
quently it is grooved or hollowed along the under surface. The tip is 
more or less attenuated and rounded, or sometimes pointed; in many 
species it is widened into a bowl or spoon, usually oval, but sometimes 
