424 



ARACHNIDA 



C. fissiceps (Cambridge). Body 1.5 mm.; abdomen round, and 

 orange in color; head black around the eyes; the head of the male 

 extends forwards, forming two humps: very common on small bushes. 



FAMILY 9. EPEIRIDAE.* 



Round-web spiders. Usually large spiders with long legs and an 

 abdomen which is rounded or ovoid and often provided with humps; often 

 brightly colored; cephalothorax short, low in front with the eyes near 



the front edge and in 3 transverse 

 groups, the 2 lateral pairs being close 

 together and separated from the mid- 

 dle eyes; 3 terminal claws on each 

 foot, usually with accessory spines 

 also. The web is round and regular, 

 with radiating spokes joined by cross 

 threads (Fig. 667). The latter form 

 2 spirals, an inner spiral that begins 

 in the center and winds outwards, 

 covering usually less than a quarter 

 of the finished web, and an outer 

 spiral that begins at the edge and 

 winds inwards, covering a large part 

 of the web. The outer spiral is 

 formed of a sticky thread which holds 

 the insects flying against it. The 



spider usually tears down its web and builds a fresh one every night: 

 this may be for the purpose of renewing the sticky thread, which gradu- 

 ally hardens. About 120 American species are known. 

 Key to the genera of Epeiridae here described : 



Cj Abdomen not elongate, usually round or ovoid. 



&! Hinder row of eyes strongly curved ; large brightly colored spiders. 1. ARGIOPE 

 6 2 Hinder row of eyes not curved or only slightly so. 

 <?! Thorax without a deep longitudinal furrow. 



d t Head and thorax separated by a deep transverse cervical groove. 2. CYCLOSA 

 d z No distinct cervical groove ; thorax usually with a V-shaped furrow. 

 Cj. Abdomen without spines. 



fi Web entire 3. EPEIBA 



/ 2 Web lacking a large segment 4. ZILLA 



e : Abdomen with prominent spines 5. ACROSOMA 



c 2 Thorax with a deep longitudinal furrow 6. MANGORA 



a a Body elongate and light-colored. 



6 X Groove between the spiracles curved markedly 7. TETRAGNATHA 



b t This groove nearly straight 8. LEUCAUGE 



* See "New England Spiders of the Family Epeiridae," by J. H. Emerton, Trans. 

 Conn. Acad., Vol. 6, p. 295, 1884. "American Spiders," etc., by H. McCook, Vol. 3, p. 

 132, 1893. 



Fig. 667 An orb web (Emerton). 

 1, inner spiral ; 2, outer spiral ; 3, 

 strand going to the nest 



