AMERICAN SPIDERS AND THEIR BPINNINdWOUK. 



(s.co). The labinm flab) and 



dco-. 



mn- 



to as "sternal cones," or simply "cones' 

 maxilla- (mx) are also shown in Fig. 92. 



VII. 



The parts of the abdomen referred to in description are as follows : 



The dorsum (Fig. 93, do) is the rounded top of the back, of which the 



anterior part is called the "base" (ha), 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 lino (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 cpi- 

 gyjium (ep)aiid gills (gi) 

 and the spinnerets (sp) ; 

 pits or dimples may also 



lie seen on the venter 

 symmetrically arranged 

 as on the dorsurn. The 

 Vn S P median ventral hand is 

 usually bordered by a 

 strip of lighter color 

 more or less broken. 

 When the abdomen is 

 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. hi some species these are hard and spinous. 



The exterior parts of the epigyiium referred to in the description are 

 illustrated at Figs. !.">, '.Hi. The alriolum vulva-, or vnlval pon-h, is a 

 vaulted porch or hood that curves over the genital opening, in 

 front of which (anterior) it is located. It is usually chilinons, 



and covered at the b;isc with hairs. The middle part i any 



species is prolonged into a shaft or scapus atrioli, which is sometimes a 

 mere llap, 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 



113. In. ill 



AllliriMKN AND I'ARTH. 



In. 11:1 hoi-sul view ; |nl jiiiinii iiiiitinK I" rciilmlotliorajc ; ha, bane or 

 fore part; cl.co, dorsal COIICK or Hhonhlri humps; fol, folium or dorsal 

 pattern; ap, apex ; sp, spiiinrrclM ; pt, pit marking insertion of musHrs; 

 mn, iiii'iliim lini- ol norsiim. In. 111. siili- vii-w ; vn, venter; ep, epl- 

 K.vnum ; g\, brralhliiR KillH ; other rcfercnccn H above. 



Epigy- 



nuin. 



