Thisisnotintendedtobeacomprehensivetextbookofentomology andarachnology, butratheraconcisesynthesisofcertainbasic informationrequiredfor BSc(Hons)andMSc(Entomology) examinations. Theapproachisprimarilyfunctional: forinstance, theskeletalandwaterproofingpropertiesofthearthropodcuticle arediscussed, butnotitsbiochemistry;andIhaveincludedonly thosepointswithwhichIbelievealladvancedstudentsofthesub- jectoughttobefamiliar. Someaspectsaretodayregardedas outdated;othersdonotappearinanycurrenttexts, butIhave includedthembecauseIconsiderthemtobeimportant. Innoway, therefore, shouldthisberegardedasabookofreference. Tobe frank, itconsistsofamassofoversimplificationsandunqualified generalizationswhichareintendedtoclarifythecomplexprinciples underlyingthem. OncetheseprincipleshavebeenthorougWy grasped, thereaderwillhaveacquiredasufficientlybroadapproach tobeabletogetthebestvaluefrommoreadvancedtreatises. MythanksareduetoDrs. JohnDalingwater, AndrewMilner, andespeciallyPaulHillyardfortheiradviceonpalaeontological matters;toProfessorsEinarBursellforpermissiontouseFig. 8, takenfromhis An Introduction to Insect Physiology(Academic Press), NeilF. HadleyandtheEditorsof American Scientistto reproduceFigs. 52,53, andtoF. SchallerforFig. 42fromachap- terhewroteinGupta(ed. ) Arthropod Phylogeny(VanNostrand Reinhold). Finally, IwouldliketoexpressmygratitudetoRoy Abrahamsforredrawingthefiguresshowinginsectwingvenations andtoEileenBerghfortypingthemanuscript. Thebookwas completedduringtenureofaLeverhulmeEmeritusFellowship whichIampleasedtoacknowledge, whileProfessorN. A. Mitchison FRSkindlyprovidedmewithaccommodationinUniversityCol- lege, London. J. L. CWUDSLEY-THOMPSON Contents 1 PalaeontologyandPhylogeny. . . . . . . . . . . . . . . . . . 1 1. 1 TheEarliestArthropodanFossils. . . . . . . . . . . . . . . . 1 1. 2 TheFirstTerrestrialArthropods. . . . . . . . . . . . . . . . . 2 1. 3 EvolutionintheArthropods. . . . . . . . . . . . . . . . . . . 4 1. 3. 1 EmbryologicalConsiderations. . . . . . . . . . . . . . . . . . 4 1. 3. 2 ComparativeMorphology. . . . . . . . . . . . . . . . . . . . . 5 1. 3. 3 MonophyleticorPolyphyleticOrigins. . . . . . . . . . . . . 6 FurtherReading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 ImplicationsofLiveonLand. . . . . . . . . . . . . . . 10 2. 1 TheSignificanceofSize 10 2. 1. 1 Size, SkeletonsandAllometry 11 2. 1. 2 AllometricGrowth 12 2. 2 WaterRelations 12 2. 3 TheConquestoftheLand 14 2. 4 . TheIntegument 14 2. 4. 1 TheEndocuticle 15 2. 4. 2 TheExocuticle 15 2. 4. 3 TheEpicuticle 16 2. 5 GrowthandEcdysis 18 2. 6 Respiration: Lung-BooksandTracheae 19 2. 7 NutritionandExcretion 21 2. 7. 1 Nutrition 21 2. 7. 2 Excretion 22 2. 8 EcologicalConsiderationsofSize 23 FurtherReading 25 3 TheConquestoftheLandbyCrustacea. . . . . . . . . . . . 26 3. 1 TypesofAdaptation. . . . 26 3. 2 TransitionfromWatertoLandinAmphipoda 26 3. 3 TransitionfromWatertoLandinDecapoda 28 3. 4 TransitionfromWatertoLandinIsopoda 30 3. 4. 1 Morphology 30 3. 4. 2Physiology. . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3. 4. 3 Behaviour 34 VIII Contents 3. 5 Conclusion 35 FurtherReading. . . . . . . . . . . . . . . . . . . . . . . . 36 4 InsectPhylogenyandtheOriginofFlight. . . . 37 4. 1 AncestryofInsects 37 4. 2 TheOriginofWings 38 4. 2. 1 Apte10taandtheAncestryofSpiders 39 4. 3 Paranota1Theory 40 4. 4 TrachealGillTheory . 42 4. 5 SelectionforFlight 43 4. 6 PhylogenyoftheLowerInsectOrders . 44 4. 6. 1 FossilEvidence . 
