402 Introduction to Animal Morphology. 



mostly tropical. Anisoscelis has dilated tibiae : some have 

 remarkable forms. 



Order 3. Thysanura {Latreille) — wingless, ametabolous, 

 living in damp, dark places, hair- or scale-clad, rarely with 

 compound eyes, but with two groups of 6-14 ocelli ; mouth 

 masticatory ; Malpighian tubes few, long ; abdomen with ter- 

 minal bristles or a bifid tail. Lepisma has the typical lower 

 lip of Orthoptera ; others have no trace of a second maxilla> 

 as in Myriopods. They include two families : — i . Poduridae — 

 cylindrical mouth, small, with no palp ; abdomen 6-3 ringed* 

 with a fork-like tail, whereby they can spring ; hairy or scaly 

 back ; prothorax small, hidden ; ocelli four (Achorutes), seven 

 (Desoria), or eight. Cyphoderus has a cup-like mesothorax. 

 Podura scales, being finely lined, are used as test objects for 

 the microscope. Smynthurus has cephalic stigmata. 2. Le- 

 pismidae — fusiform, with small metallic scales and many- 

 jointed antennae ; abdomen ten-ringed, with five end-bristles, 

 of which the middle is the largest. Machilis (Petrobius) has 

 compound eyes. Nicoletia is blind. Lepisma, the scales of 

 which are also commonly used as microscope tests, lives in 

 sugar. 



Order 4. Thysanoptera {Haliday) — small, flattened, found 

 in vegetables ; head cylindrical ; mouth suctorial, directed 

 downwards and backwards ; maxillae fused with the labrum ; 

 mandibles bristle-like ; antennae 8-9 jointed ; eyes large ; 

 ocelli present ; maxillary palp 2-3 jointed ; labial two-jointed ; 

 prothorax small ; wings two pair, equally long, bristled, not 

 folded, with few veins ; rarely short or none. Tarsi two-jointed, 

 with a sucking disk and no claws ; intestine about twice as 

 long as the body ; malpighian tubes four, free at the tips. 

 The females of Thrips have a compressed four-valved ovi- 

 positor. Phloeothrips has a tubular last abdominal segment 

 in both sexes. 



Orders. Euplexoptera {Weshvood) : Earwigs — head free; 

 clypeus short ; labrum large, crescentic ; labium cleft to the 

 base of its stipites ; ocelli none ; eyes over the thread-like 

 12-40 jointed antennae ; prothorax quadrangular ; hemielytrae 

 much shorter than the abdomen, with no membranous area ; 

 hinder wings thin, fan-like, with radial costae, useless for 



