Superfamily Argiopoidea 



are laid early in the season, and the young soon hatch. They arc 

 guarded by the parent female until they disperse. On the ap- 

 proach of winter the young make the sac-like nests in which to 

 pass the winter. 



The Attidas is one of the largest and most widely distributed 

 of the families of spiders; representatives of it are found in all 

 parts of the world except in the polar regions and several thousand 

 species have been described. They are especially abundant in 

 the tropics; and nearly three hundred species, representing more 

 than forty genera, are known to occur in America north of Mexico. 

 A revision of the American species of the family has been 

 published by Mr. and Mrs. Peckham (09) in which are given 

 detailed descriptions of all of our known species; this work is 

 indispensable to one making an exhaustive study of this family, 

 and has been freely used in a revision of the following account, 

 which was mostly written before the appearance of the work of 

 the Peckhams. 



1 have omitted descriptions of some Mexican genera, repre- 

 sentatives of which are found in this country only along our 

 southern border, also of some genera represented only by one 

 or two rare species; and in case of the larger genera, it has seemed 

 best to include accounts of only the more common species. 



The genera of this family are grouped by Simon into three, 

 somewhat artificial sections, which are distinguished by the nature 

 of the armature of the lower margin of the furrow of the chelicerae, 

 as follows: 



I. With the lower margin of the furrow of 

 the chelicerae armed with several, iso- 

 lated teeth forming a series (Fig. 739, 

 a). Attid/e Pluridentati 



II. With the lower margin of the furrow of the 

 chelicera? armed with a single tooth or 

 unarmed (Fig. 739, c). 



Attid/e Unidentati 

 III. With the lower margin of the furrow of 

 the chelicerae armed with a large tooth 

 which is compressed so as to. form a keel, 

 and divided into two points by a notch, 

 rarely truncate or furnished with a serrula 

 (Fig. 739, />)• Attid/e Fissidentati 



663 



