374 Introduction to Animal Morphology. 



constricted at the origin of the first pair of limbs, and also 

 behind the head ; ocelli 2-6 ; legs equal ; long, thin, with 

 separate claw-joints, living in damp earth. 



Order 2. Araneina, Spiders — having the unjointed cephalo- 

 thorax and the saccular abdomen united by a narrow pe- 

 duncle; breathing by tracheal lungs and tracheae; mouth 

 masticatory, rarely with no labium (Aphantocheilus) ; anten- 

 nary jaws pierced by the poison duct ; eyes 6-8 ; spin- 

 ning warts posterior, rarely only two (Stenochilus Hobsoni); 

 stomach annular, surrounded by the voluminous liver. There 

 are usually two tracheae behind the tracheal lungs, and the 

 sex-openings are between the lung stigmata. The non- 

 chelate palps are simple in the female, but in the male they 

 are swollen at the tip and grooved beneath, and have several 

 hook-like appendages ; by these the spermaphores are placed 

 in the female vulva. They are predaceous, with often comb- 

 like paired claws, and undergo no metamorphosis, but moult 

 frequently. There are two Sub-orders : — i. Tetrapneumones 

 {Latreille) — with four lungs and stigmata, and four spinne- 

 rets, of which two are small; ocelli eight, close together; 

 large spiders, forming one family, Mygalidae, with long, 

 foot-like palps, with two end claws; many of them dig bur- 

 rows, which they line with web-material, and for which they 

 form a lid fastened by a silken hinge (Cteniza, Atypus, &c.). 

 Mygale, with down-directed antennary jaws and screw-like 

 copulatory palp, is said to attack small birds. Sub-order 2. 

 Dipneumones {Laireille) — lungs two; stigmata two or four; in 

 the latter case, as in Segestria, Dysdera, &c., the hinder pair 

 open into tracheae ; spinnerets three pair ; antennary jaws, 

 with indirected claws ; ocelli scattered. The families are : 

 I. Araneidae — sedentary web-spinners, with ocelli in two 

 transverse rows : some are tube- or flask-spinners (§ Tubi- 

 telae), having the second and third pair of legs shorter than 

 the first and last. Dysdera has four eyes in the first row, 

 two in the second. Nops has but two eyes. Segestria has 

 three rows, each of two eyes. Drassus has eight unequal eyes. 

 Clubiona has eight eyes, of which the four hinder and two 

 extreme of the front row form a crescent. Argyroneta (the 

 water-spider) has straight rows, Tegenaria (the house-spider) 



