THE FSEUDOSCORinONS OF CALIFORNIA 



N \T11 \ \ 11 \NKS 

 II. S. DEI'T. AOHICULTI'RK, WASlllNUTON , I). C. 



The Pseudoscorpions are a very strongly circuiiiscril)i-d group of tlic Arai-li- 

 nida. Of tlie general a|)pearance of diminutive scorpions tliey differ in so many 

 important structures as to be far removed from tliem in the system. They lack 

 the post-abdomen or "tail" of the scorpions, and consequently the sting; they have 

 no median pair of eyes, no sternum, no pcctines, and there are various differences 

 in tiie legs and mandibles. Tlie scorjiions have four pairs of stigmal orifices on the 

 venter of the abdomen, whereas the pseudoscorpions have but two pairs of stigmata. 

 Practically all authors put them in an order by themselves, variously called 

 Chclonethi, Chernetidea or Pstudoscorpionida. Their relationships are considered 

 to be closer to the Plialangida and Acari than to the scorpions. The body of a 

 Pscudoscorpion, or Chelifer, is seen to be of two principal parts, a large front 

 part, not or only indistinctly segmented, the ccplialothorax; and a segmented 

 posterior part, broadly attached to the cephalothorax, the abdomen. Attached to 

 the front of the cephalothorax are the mandibles, chelicera- (or antennse of some 

 authors), and a pair of long |)alpi ending in a large claw, these are the pcdipalpi. 

 The legs are attached to the under surface of the cephalothorax, their coxa being 

 approximated. The dorsal surface of the cephalothorax often bears on each 

 anterior side one or two eye-spots, but there are a number of eyeless sj)ecies. In 

 some forms there are one or two transverse furrows or grooves on the cephalo- 

 thorax, and the surface is often granulated or roughened. 



The mandibles, or chelicera-, are rather small, but in some forms large and 

 conspicuous; they are of two joints, a large basal joint called the hand, or jjaturon, 

 and a slender, curved apical joint or finger; the tip of the paturon is prolonged 

 in a process of similar size and shape to the apical joint, the two lingers forming 

 a claw. The apical joint is called the movable finger, and the other the immovable 

 finger of the mandibles. The basal joint often bears a more or less branched 

 process, the Hagellum ; while the movable finger often has a comb-shaped process 

 attached more or less closely to its inner edge; this is the scrrula. The movable 

 finger bears an apical process, sometimes reduced to a tubercle, but usually slender, 

 called the galea, or stylet ; this contains the aperture of the silk glands, which are 

 situated in the cephalothorax. The structure of these parts is of great value in 

 classification. The pedipalpi consist of six joint.s; the basal is the coxa; then 

 follow trochanter, femur, tibia, and the hand ending in two curved fingers which 

 form a claw ; one finger is movable, the other but an extension of the previous 

 joint. Each leg is composed of a coxa, trochanter, femur (usuallj- divided), tibia 

 and a tarsus of one or two joints. The femur usually shows at its Iwse a triangular 

 part cut off by a suture from the main portion. This basal piece is the trochantin. 

 In some species it is so distinctly separated from the femur as to ap|)ear as a 

 separate joint. The tarsi end in a pair of siniph- el;iws. and in some cases a 

 membraneous ambulacrum, or arolium. 



