842 CLASS V. ARACHNIDA. 



belongs with some exceptions to the hotter regions of the Old World. 

 Phalangodes, the European species, has also North American and Aus- 

 tralian representatives. Mermerus, Epidanus, Maracaudus and Sitalces 

 are tropical genera. 



Fam. 2. Gonyleptidae, this family is distinguished from the preceding 

 by the absence of a longitudinal stripe on the cephalothorax. They are 

 exclusively American, Gonyleptus. 



Fam. 3. Cosmetidae, also from America. 



Sub-order 3. PLAGIOSTETHI. 



The last three segments are free or their segmentation is indicated by 

 striae ; the anterior abdominal sternum is pushed forward as far as the 

 first pair of coxae ; prosomatic sternum very short ; a single claw on all 

 the legs. Mostly denizens of temperate regions. 



Fam. 1. Phalangiidae. Integument soft or coriaceous ; two eyes on 

 an eminence well removed from border of cephalothorax ; the 2nd pair 

 of legs have well-marked gnathobases ; the tarsus of the pedipalps is 

 much longer than the tibia and ends in a claw. Sclerosoma with 2 British 

 species ; Mastobunus ; Astrobunus ; Liobunum with 2 British species has 

 very small body and very long legs ; Prosalpia a high mountain form ; 

 Phalangium (Figs. 549, 550) the form commonly seen on walls, has 4 

 British species ; Dasylobus, Platybunus, with 2 British species ; Megabunus 

 with 1 species found in our islands ; Gyas the largest member of the 

 family, Oligolophus (Fig. 551) has 8 British species ; Acantholophus as its 

 name indicates is a spiny form. 



Fam. 2. Ischyropsalidae. Coriaceous, with a longitudinal stripe ; two 

 eyes on an eminence removed from the border of the cephalothorax ; 

 coxae free ; gnathobases of 2nd legs reduced to tubercles ; pedipalps 

 long with no claw, their tarsus is shorter than the two preceding joints. 

 Sabacon lives in caves and grottoes ; Ischyropsalis in the same localities 

 and in moss. 



Fam. 3. Nemastomatidae. Coriaceous, no stripe on cephalothorax ; 

 2 eyes on an eminence near the anterior border of the cephalothorax ; 

 coxae free ; pedipalps as in preceding family ; no gnathobase on 2nd pair 

 of legs. The single genus Nemastoma has 2 British representatives, they 

 live in moss and the damp debris of forests. 



Fam. 4. Trogulidae. Very hard, firm exoskeleton ; cephalothorax 

 produced in a bifurcated hood with overhangs mouth ; coxae fused to 

 cephalothoracic sterna ; no gnathobase on 2nd pair of legs ; pedipalps 

 moderate or short ; their tarsi and claws as in preceding two families. 

 They are rather mite-like Phalangids with deliberate movements. Dicra- 

 nolasma, Anelasmocephalus with 1 British species ; Calathocratus ; Trogulus 

 with 1 British species ; Metopoctea. 



Order 9. ACARINA (Mites).* 



Degenerate Arachnids allied to the Phalangids. The abdomen 

 is usually unsegmented and broadly fused with the thorax. The 



* O. Fr. Miiller, " Hydrachnae," etc., 1781. A. Duges, " Recherches 

 sur 1'ordre des Acariens en general et les families des Trombidies, Hydra- 



