XII] 



SCORPION1DA 



271 



Both the chelicerae, which are small and short, and the pedipalpi, 

 which are long and six-jointed, end in nippers, the latter recalling 

 the appearance of the claws of a lobster. The four pairs of walking 

 legs end in claws. 



The mouth is very minute, for like the Spiders Scorpions only 

 suck the juices of their prey. They feed for the most part on 

 Insects and Spiders. The basal joints of the first two pairs of 



B 



FIG. 123. 



A. Vertical section through a lateral eye of a Scorpion, Euscorpius italicus. 

 B. Diagram of retinula of a Scorpion's central eye. C, D, E. Trans- 

 verse section of B taken at different levels. From Lankester and Bourne. 



1. Cuticular lens. 2. Epidermis of the general body-surface. 3. Base- 

 ment membrane. 4. Epidermal cells which contain pigment. 5. Nerve 

 end-cells with nuclei. 6. Khabdorne. 7. Fibres of optic nerve. 



8. Pigment contained in connective tissue cells. 



appendages, like those of the pedipalps in Spiders, are all produced 

 towards the mouth, forming gnathobases which probably help to 

 hold their food. 



The eyes of Scorpions are simpler than those of Spiders and are 

 amongst the simplest type of eye found amongst Arthropoda. As 

 Fig. 123 shows, the lateral eyes are simply shallow pits of the 

 ectoderm. The cells forming one of these pits secrete more cuticle 



