CENTIPEDES AND MILLIPEDES 397 



pedes of tropical countries, feared on account of their painful bite, 

 constitute a widely-distributed family, including larger and longer 

 forms, provided with twenty-one pairs of legs. Some of them 

 may be as much as a foot in length. A well-known species is 

 Scolopendra morsitans. Another family of Centipedes, found all 

 over the world except in the coldest regions, includes slender 

 elongated forms, which are devoid of eyes, and burrow under- 

 ground in pursuit of earth-worms. Some of them are phosphor- 

 escent (fig. 243), as, e.g., the common British species {Geophilus 

 longicornis). 



Order 3. — Spider -LEGGED Myriapods (Schizotarsia) 



Spider - legged Myriapods include the species of a genus 

 (Scutigera) which is widely distributed through the warmer parts 

 of the globe. The body is comparatively short, but antennae 

 and legs are very much elongated. The eyes are compound, 

 a unique peculiarity in the class. The breathing organs differ 

 considerably from those of ordinary Myriapods, and open to the 

 exterior by a single row of stigmata placed in the middle line 

 on the upper side of the trunk. They are very active creatures, 

 and most of them pursue their prey in broad daylight, even 

 when the sun is strong. 



Order 4. — iNSECT-LiKE MYRIAPODS (Symphyla) 



Insect-like Myriapods include but one genus {Scolopendrella), 

 of very small size, and represented by a number of widely-distri- 

 buted species, of which two are British. The adjective " insect- 

 like " is used on account of the very strong resemblance which 

 exists to the primitive insects of the order Thysanura (p. 384), 

 and some zoologists go so far as to state that we should look 

 upon these forms as coming very near to the ancestral stock 

 from which insects have been derived. There is at any rate 

 a close relationship. 



Order 5. — LARVA- LIKE MYRIAPODS (Pauropoda) 



The order of Larva-like Myriapods includes certain exceed- 

 ingly small creatures first discovered in Britain, and thought 

 at first by their discoverer (Sir John Lubbock) to be larv^. 



