6,^4 I'OMONA C'oLLEGf: JomNAI- OF ENTOMOLOGY 



The abdomen usually shows eleven segments above and nine below. Each 

 segment has a chitinous plate on the dorsum ; in many forms divided longitudinally 

 so that there is a pair of sclerites on each segment. 



There are four stigmata near the base of the venter. Close up to the hind 

 coxae is the genital lobe, which is sometimes traversed by folds, or grooves. The 

 body and appendages are sparselv covered with hairs, in some species some or all 

 are clavate. 



There is but little external difference between the sexes; the abdomen of tin- 

 male has the segments more closely pressed together, and often the edges are more 

 angulate, or more roughened than in the female ; the legs may be more slender in 

 the male, or the pedipalpi more thickened. There are few, if any, specialized 

 secondary sexual characters, and no cases of protective coloring or of mimicry are 

 as yet known. There is rarely anj' pattern of markings, their color being of a 

 yellowish to reddish brown, or sometimes nearly black; a few are more or less 

 greenish. 



Chelifers occur nearly all over the world, except in very cold regions, but 

 are more abundant in the tropics than elsewhere. In the tropics a few species 

 live exposed on the foliage, but the great majority of species shun the light and 

 are only to be found under bark, among dead leaves, on the ground, under stones 

 or in caves. A few species occur on the seashore, and do not appear to mind 

 the salt water. 



Normally the}' walk slowly forward, with the pedipalpi extended; when dis- 

 turbed they retreat quickly backward by a sort of jerky motion. It is evident that 

 their eyes are not useful in recognizing objects, and touch seems to be their 

 most important sense. The}- feed on minute, soft insects and mites ; many catch 

 Collembola. Some, perhaps all, species hibernate in the adult condition, often in 

 a little nest formed of bits of wood held together by silken threads ; one such nest 

 was 4 mm. long and 2 mm. broad. Some species, perhaps all, mate in the spring. 

 and the female carries her eggs in a mass attached to the base of the abdomen ; the 

 young (of C. cancroides) hatch in July; ])robably there is but one brood a year, 

 and the individuals live for several years. 



Various species, mostly of the genus Chelanops, have been found attached to 

 insects, often to flies. Several explanations have been suggested, such as for migra- 

 tion, accidentally seizing the leg under the impression it was food, etc. Some 

 species have been taken from under the wings of beetles. The genus Chelanop-i 

 is blind, and it apparently seizes any moving object that comes close to the palpi; 

 thus clasping a fly's leg it holds on under the impression that the prey will soon 

 tire. It undoubtedly also serves as a means of distribution. A summary of 

 these cases of insects carrying pseudoseorpions is given by H. W. Kew.* 



The genera known from the Pacific coast may be distinguished by the fol- 

 lowing table, two of them have not yet been recorded from California: 

 1. Cephalothorax with a transverse groove; abdominal scuta^ divided; 

 mandibles small, with a stylet; the serrula att.iclRil above to the 



*Anur. Naturalist, '.i .luly. liMU. i)|). U).S-21.). 



