622 THYSANURA. 



THYSANURA. 



The Thysanura are wingless, and undergo no metamor- 

 phosis. There is a great range in the degree of complexity 

 of structure from Lepisma, the latter resembling a larval 

 Perla or Blatta, to Anura. The higher group, or bristle-tails, 

 which we may call Cinura, comprises the families LepismatidcB 

 and Gampodem. Lubbock has applied the term Collembola to 

 the Poduridaj and Smynthurida^, in allusion to 

 the sucker-like organ situated at the base of the 

 abdomen. The Ginura are characterized by 

 their well-developed mouth-parts, abdominal 

 feet and bristles or cerci, and the Collembola 

 by their spring [elater), its holder (tenacuhau, 

 Fig. 617a), as well as the sucker or collophore^ 

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



parts and by their diminutive size. pjg gj.j,^ 



These interesting small, wingless forms also afford a pas- 

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

 pendrella being a connecting link, having the head and antennae 

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

 the i)lace of abdominal legs in Lepisma is supplied by the 

 rows of small stylets which prop up the long slender 

 abdomen. 



Lepismatid^ 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 antennae are ver^'^ long, setiform, 

 many-jointed ; the month-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 Avith 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 Mj-riapods. 

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



