118 



NATURAL HISTORY OF ARTHROPODS. 



FIG. 169. Attus, 

 jumping spicier. 



SUB-ORDER I. - - DIPNEUMONIA. 



These forms have but two pulmonary sacs, and two or four stigmata. When the 

 latter number are present, two of them open into a regular tracheal system. The man- 

 dibles work laterally. There are six pairs of spinnerets, and usually 

 eight ocelli. This sub-order contains the great majority of the 

 spiders, and we need here to mention but a few of the most im- 

 portant families, and some of the prominent forms. 



The jumping spiders form the family ATTID^E. These have the 

 body short and the cephalothorax large and square. The eyes are 

 usually arranged in three transverse rows. They spin no web, 

 but capture their prey by leaping upon it. Some of the species 

 are very common. Before leaping some of the forms always fix 

 a thread on the point from which they jump. By this they are 

 suspended in the air if they miss their aim, and are thus secured 

 from falling far from their hunting-grounds. 



Closely allied to the Attidre is the family LYCOSID^E. Like the 

 last they make no webs, but capture their prey by running. Their long legs (the hind 

 pair the longest) enable them to run very rapidly. The arrangement of the ocelli is 

 shown in the cut. The cephalothorax is narrowed in front. Possibly the best-known, 

 certainly the most celebrated 

 species, is the Tarantula, Taran- 

 tula, apidice, which lives in Italy 

 and Spain. It is fabled that the 

 bite of this spider produces epi- 

 lepsy, or dancing madness, in its 

 victims, which could only be re- 

 lieved by a particular kind of 

 music. The species of Lycosa 

 and Dolomedes, another genus 

 of the family, are very numerous. 

 They live on the ground, under 

 stones, etc. 



The TIIOMISID^E have re- 

 ceived their common name, 

 Crab-spiders, from the fact that 

 some species like the crabs walk 

 better sidewise that in the nor- 

 mal direction. They have the 

 abdomen broad, the ocelli of nearly equal size, and arranged in two parallel urcuate 

 rows. They make no regular webs, but spin single threads by which they fasten 

 leaves together to make their homes. 



The family EPEIRID^E contains some of the most showy examples of the Arachnida. 

 The two first pairs of legs are longer than the others, and the eyes are widely separated. 

 They make circular webs, consisting of radiating threads crossed by a spiral. Epeira, 

 with its numerous species, is the typical genus, and one species has served for our ana- 

 tomical account of the Araneina. In this genus the abdomen is nearly globular. In 



FIG. 170. Tarantula apulice, tarantula, natural size. 



