622 THYSANURA. 



THYSANURA. 



The Thysannra are wingless, and undergo no metamor- 

 ]>]iosis. There is a great range in tlie degree of complexity 

 if structure from Lepisma, the latter resembling a larval 

 Porta or Blatta, to Anura. The higher grou]>, or bristle-tails, 

 which we may call (Jinui'd, comprises the families Lepismatuln- 

 and Campodem. Lubbock has applied the term Collemhola to 

 the Poduricbv and Smynthurida^, in allusion to 

 the sucker-like organ situated at the base of the 

 abdomen. The Clmrra are characterized by 'f/ 

 iheir well-developed mouth-parts, abdominal 

 feet and bristles or cei'ci, and the Collembola y^ 



by their si)i-ing [elater), its holder (tenaculum, A 



Fig. 6l1r/), as well as the sucker or collopliore, 2 



as it may be termed ; by the rudimentary mouth- '-'''^ 



parts and by their diminutive size. " ptg g^-^ 



These interesting small, wingless forms also afford a pas- 

 sage froni the true winged insects to the Myriopods, Scolo- 

 ])endrella being a connecting link, having the head and anteninv 

 of Canipodea, and the abdominal legs of the Myriopods. Even 

 the place of abdominal legs in Lepisma is supplied by the 

 rows of small stylets which prop up the long slender 

 abdomen. 



LepismatiDjE Burmeister. Bristle-tails. These agile crea- 

 tures, which are revealed by turning over stones and sticks in 

 damp situations, and are often seen about houses, have a long 

 flattened body, with metallic scales, in form somewhat like 

 those of butterflies. The antennoe are very long, setiforni, 

 many-jointed ; the mouth-parts are free, with long palpi ; the 

 maxillary palpi being seven-jointed and the labial palpi four- 

 jointed. The mandibles are stout, sunken in the head, and 

 armed with teeth for gnawing. The prothorax is very large, 

 and all the rings of the body are of much the same size, so 

 that the insect bears a general resemblance to the Myriapods. 

 The anal stylets are long and large, which with the smaller 



