194 ARACHNIDES, PULMONARY. 



in which their ova are inclosed. These webs or snares, of excessive tenuity, and con- 

 structed with so much apparent art, are of various forms ; sometimes floating in the air 

 in single threads, or suspended in concentric circles crossed by numerous rays ; in 

 others of a thicker fabric, in which the interstices between the threads are not percep- 

 tible. One species inhabiting caves forms a web which rivals snow in whitness ; an- 

 other constructs a cylinder between leaves ; while others attach to trees and cor- 

 ners of walls irregular webs of no determinate form. The spider itself, uniting to 

 strength the attribute of cunning, watches the approacli of its prey in a situation 

 ready to pounce upon the imprudent insect which wanders into the snare. Some 

 species suck the juices of flies ; others devour them entire. They are in general ca- 

 pable of long abstinence, and pass the winter in a kind of torpor. From the ob- 

 servations of Pelletier, it appears they have the faculty of reproducing their members 

 when destroyed by accident. Spiders generally breed once a year, in temperate cli- 

 mates towards the end of summer or commencement of autumn. They are all ovi- 

 parous. Those which form webs envelope the ova in a kind of coccoon made of the 

 silky matter, consisting of two layers, the internal one of a finer quality than the 

 outer layer. Various experiments have been made to turn the silk of the spider 

 to account in the arts ; and gloves and other small articles have been manufactured 

 from the threads of some species. Spiders are useful in restraining the multiplica- 

 tion of insects ; and they themselves form the favourite food of many birds. 



I. TETRAPNEUMONES. 

 With two spiracles and two pulmonary sacs on each side. 



The eyes of this family are always situate at the anterior extremity of the cephalo- 

 thorax, and generally approximated. Their mandibles are strong ; the feet ro- 

 bust ; the fourth and first pairs, and in some the posterior pair, being largest The 

 greater number have four spinning papillae, and construct silky tubes or bags, either 

 in cylindrical holes or under stones, or between the leaves or under the bark of trees, 

 where they remain concealed. They leave their holes at night to seek their prey, 

 or watch the passage of the small animals which form their support near the en- 

 trance of their cells. This family includes the larger species of Araneides, such as 

 are known in the Antilles under the name of Crab-Spiders. 



Gen. 4. MYGALE, Lat. 

 Palpi projecting, elongated, pediform, inserted at the extremity 



of the jaws ; mandibles with their hooks bent downwards ; 



two elongated jaws; labium very small and quadrate ; eight 



eyes. 

 M. amcularia, Lat. Bird-catching Mygale. Blackish, very hairy, 



the hairs elongate ; palpi and legs with ferruginous tips ; tarsi 



broad ; claws not exserted ; palpi of the male globose. Of large 



size. Inhabits S. America. Shaw, vi. pi. 129. 



This species resides among trees or holes in the ground, devours ants, and some- 

 times kills small birds in their nest. 



M. ccementaria, Lat. Ferruginous brown ; mandibles blackish ; cari- 

 na and margin of the thorax paler. Inhabits South of France. 

 Lin. Trans, ii. pi. 17, fig- 6. 



Gen. 5. ATYPUS, Lat. Oletera, Walck. 



Body oblong, and eight feet ; eyes on each side, geminated ; 

 lip very small and quadrate, inserted under the base of the 

 maxillae ; palpi inserted at the external base of the maxillae. 



A. Sulzeri, Lat. Black and shining; mandibles very long and strong; 

 thorax nearly quadrate, elevated before, plain behind ; joints of 

 the legs whitish. Inhabits France and England in holes in the 

 ground Lat. Gen. i. pi. 5, fig. 2. 



