ARANEAE 415 



mental fold, and between them is the genital pore which, in the 

 female, is covered by a plate, often complex in structure, called the 

 epigynum. 



The arrangement of the internal organs of spiders will be seen in 

 the accompanying diagram (Fig. 654). 



Spiders prey principally upon insects, but will usually kill and 

 devour any animal smaller than themselves, including their own kind. 

 The female not infrequently eats the smaller male when he approaches 

 her at pairing time. Spiders may be divided, as to their method of 

 taking their prey, into 2 groups: (1), the hunting spiders, which run 

 on the ground or on plants and spring upon their prey, usually from a 

 concealed retreat, and (2), cobweb spiders, which make webs to catch 

 flying insects. The hunting spiders often make nests of silk; the cob- 

 web spiders usually live in their webs or in nests near them. 



The webs are of 4 kinds: (1), the very irregularly woven web of 

 the house spider Theridion tepidariorum and other Theridiidae (Fig. 664) ; 

 (2), the more or less 

 irregular web of the 

 Linyphiidae and some 

 other spiders, the most 



important part of which 



consists of a large, flat 



or curved sheet held " j / ^ *& 



down by threads in all 



directions (Fig. 665) ; Fig. 654 Internal anatomy of a spider (Shipley). 



/0 \ xi .e , , 1, eyes; 2, poison gland; 3, mouth; 4, brain; 5, 



(d), the tunnel webs Ot diverticulum of the stomach ; 6, lung; 7, genital pore; 



,,.,., . , 8, silk glands; 9, anus; 10, spinnerets; 11, ovary; 



the Agelemdae, consist- 12, kidney tubule; 13, intestine; 14, heart; 15, liver 



* n , ^ -, ducts, the liver having been removed ; 16, sucking 



ing of a flat sheet and stomach. 



a funnel leading to a 



retreat; (4) the round webs of the Epeiridae, composed of threads 



radiating from a common center, with cross threads (Fig. 667). 



Spiders lay spherical eggs which the female winds with silk into 

 a spherical or oblong mass called the cocoon; this the spider often 

 carries about for awhile in the mandibles or attached to the spinnerets, 

 and fastens in the web or to grass or other objects, or hides in her nest. 

 Some spiders construct burrows in the ground in which they deposit 

 their cocoons. Spiders live usually less than a year. Great numbers, the 

 adults of which die in the autumn on the approach of cold weather, pass 

 the winter in the form of eggs, while others lie torpid among leaves on the 

 ground and in other protected places. Spiders are born with the form 

 of the parent, but often differ from them at first very much in appear- 

 ance; they are also sexually dimorphic, the males being smaller than 



