Centipedes. 113 



British form is phosphorescent, and another is 

 described as capable of giving electric shocks. The 

 body consists of many segments which, with 

 the exception of the head and the last joint, 

 are similar in appearance ; the* head bears 

 the eyes, which are usually simple like those 

 of spiders, and generally in two rows. Near 

 these there are the sensitive, slender, thread- 

 like, antennae, consisting rarely of seven, 

 usually of fourteen joints or more. These 

 animals are usually carnivorous and have a 

 strong pair of mandibles, situated on each 

 side of the mouth, and two pairs of maxillae, 

 either or both of which are sometimes united 

 together in the middle line, forming a lower e (/,SL-* 

 lip for the mouth ; the anterior of these have blu) ' 

 jointed palps. The hindermost segment of the body 

 has often a pair of long limbs directed backwards. 

 There is a straight digestive canal with a number of 

 tortuous glands appended to it, .and a long tubular 

 heart made up of a chain of chambers one in each 

 segment separated from each other by valves. 



On each side of the body open the mouths of the 

 tracheae or tubes for breathing ; there may be one on 

 each segment or one on every second joint Each 

 opening is the beginning of an air-tube, which on 

 entering the body branches irregularly, the fine 

 branches freely communicating with each other. To 

 keep these tubes open there is a spirally coiled thread 

 of chitin in their lining membrane, which like a spring 

 prevents them from collapsing, and to keep the mouth 

 from being choked there is usually a raised margin 

 I 



