Pscudoscorpiones. 



105 



by a single plate, which, however, sometimes shows traces of Table-case 



segmentation. There are no median eyes, but one or more lateral ^°- ^*' 



ocelli may be present. The fingers of the chelicerae are furnished 



with delicate membranous structures called the " serrula " and 



"lamina" respectively. The moval^le finger of the mandible is 



furnished with a branched or styliform structure called the " galea," 



or with a little terminal tubercle ; and it is on this structure that 



the orifices of the silk-glands debouch. The palps are large and 



chelate, as in the scorpions. There is no constriction between the 



cephalothorax and the abdomen (opisthosoma), but the large dorsal 



plate of the praegenital segment (which is generally suppressed 



in the Euarachnida) lies between these 



two regions. Eleven abdominal somites 



can often be distinguished, and none of 



them are narrowed to form a tail, but 



the last of them is very small and is 



often hidden within the segment which 



precedes it. 



The Pseudoscorpions are small 

 Arachnids, which live under stones or 

 the bai-k of trees or in moss. They 

 are occasionally found in houses, 

 amongst books, etc., and several species 

 have been found on merchant-ships ; 

 not uncommonly specimens may be 

 met wdth clinging to the legs of flies or 

 beneath the wing-cases of beetles. One 

 of the British species (Ohisiaiii )iiari- 



iininni) is found under stones or beneath seaweed below high -water 

 mark. Their food consists of mites or small insects. At the 

 breeding season the female envelops herself and her eggs, which 

 she attaches to the under side of her body, in a spacious silken 

 cell. 



A similar cell is spun as a protection whilst the animal is 

 moulting and during iiibernation. 



The earliest-known fossil forms of Pseudoscorpions are from 

 aml)er deposits of Oligocene age. x\t the present day the group 

 is distributed all over the temperate and tropical countries of the 

 world. 



It is divisible into two sub-orders : (1) Pancfenodacii/ti, 

 (2) Hcmictenodactyli . Drawings illustrating the main points of 

 difference between these sub-orders are placed in Table-case 24. 



Fig. 68. 



Chrlifcr cancroides, 

 (After Berlese.) 



X 5. 



