Pyle ahah: 05 FEE DOR ved haar nedelrepenened bp ee bi omant be Sese ed seanedans: beef A IMAG ang i Pea nada tage a letaielahetotata Bein tosF agit te y I FE reer arte Usui ieab eiebagee gre r oh a4 tye ¥ Ny (Seb eys fisilocy dy! Hite beneainrs) e vik \niaesa W ‘ i iiesee UL REM Fae vig hon ate cas MM aesbrtan tore ott sf otreseetaes fet Rena tnatih Histon, tribesacheatinebeeunesactnet VA Mo shee WAM oPat MR oMedin: seated Hae anemelitonige acl trappaiiatetaba He Heat anatase SHdibeinied slabyaaaetststes sey a sheesiiaty wht Hide et ened ta Bieta sR mrrneyy my ttt ‘ yaieeseetdliaaat esgenibene ie fatcy aligneatta she Sa ents soln hea eves at efemancastst rests Y abet 4 odsiieh saedatoust pAeavacy op rane Hf at ; est} beahiy taal eset rein dee bes : st 5 een iE fant oats Pree pedi ftshelt tin tells hofieuseedie sceatoenn ate ; a egen mrp apes ities oevtobeasy = idustatareesnesaa ten, are atpediee f ‘ tachrgoealctgrannents i is \easils fe case ‘ yt tal Me AiatoMed bay Hehe bl vesuivarteeesgentnn niin, pip as Bparurnseien tye! ate Cabri) sneterennin bstaeturraentosgeataane picts setet . sits niser edu sennengtcseeteag art aeamie toate Hele tes feist io ‘ éibilny stan sdecellieri at Fad vaapaneasgs peasy M4 stise ter do fetes ; i daindsc stiiatsae lahvicteea| Mebiban iedip epee tga eet shviestian tance aregeady est t : 2. h sihotdasdiocedod ietseeareeaeeenite het chee Setiyiaen tel veen 3 etiot Senne pea tb oes vests lasiorsersl werd cast fea rerey tis erdatecaete Wate iatinoatinirets pesos mine Hesabett ves JLSIN0Mtohul oMe eoendAGale yafas efel edod edt Aadlbrds ae rhitee ncucenanress ee ot bats op reteien nota tebe ry ened asf f sett te . esas “Ee Ste -aneobacteote aenidcaurpi state festa tgs wld ofens Nea editeat fais taee ree > sy desatay pa tanetoferiectedtsetieat tt Sissel te peel Me 8 . ieatioaspeanies sition aid veritebederiti aes meres rar ta rd cheastad ot part 42°38 soAk masta aee itches stokeas {hole Hates Hef macart atecneaie ere) aa hah ogine ieee ol 50401 ad oly S406, eh ne delet od Ht dt vg LPS) PU thmeabepedcie te le sot ne Seooouviatet eteseseendei hgeeet poets pene ver cmainenet ed Vidal pa bose pot fetiumee) 4h PeVrraerirs Peat ay ined ray ae feria gee f (taal itary STH hgh reset eets gas vahieoamiiodeys ited ects rnetg erst veavovaeigety corer Fssot44 evn cast pues ternal Y + Apart sd fecnslden Mt Shoten caoh eaten t WO hPOE NOY oh Lb aGedemege cit teed isbebaed fans Abed te a 9464 i eer adil at de bastanlss ise Hay (reablaradet tlt stl Hidielel apt ey) nobis abcess tang jarsiveettd beaddt wbed gagatts 9s apis ancien wionepi band vet obi iAv% way. Sine asst aoenaa toate it Mritfedtions linearis, Mittin are Mae hoartnitedelidstd ape SHet Rabies 413 tatty fs AOE tava gedetal e1ok WHC au 4lbo8 De seer pias uiefeen ian Mae ashe tenuis iota fe i tor Siete tes Heber diet fogs rs HAs boiute e hoom Shae eae hide Mites olde ae Tih cats deed tem) oad pest cd nek toate peuanatteaein st ia irnraonnes (ote Fit adabiPoesusinntiHia limps Lite Hlovt lot rese ats SST ets Miaons sirearbgnaceiee espera rry4 i iM Fela aad Blase athe tieg * - (en ateletget hips laicat ie) Sitedertajuntiey nT 4 Bhaetlewett ubeieagih ad NNVes s LMcasiideyen! teentnnces on eloiingets pat sve WHldsaosie sures font r ets tur ee Hebe vets fevelbiwlitcnesiahiier cote, a teevutenni ts hinf Tayi tteat SEE MoT ttt ane! HOD ifs luentacatng Hh obs) att aericaevogid doe 4teteT wbag tare He Bet TLs Koes aieéel)l Chm torigetg rar stot ihe taatatar oe, aut tnl antes tate ra “ uate hea yh Mera Todt tenant ohare pir tpane + 120841) o6 Heo HERRON arene rob ode Lalli 0g: saat fuga ath ney) “4 Fife Then H J M965) 904 640 Ba oe M4 Cy, thd . eosin t \eevhades beige! ef tt yptee. a arenes Cubitt nisin eecongie etcen atest iain ttiemiaintiutestumerragant titniMale| dieu wsteaeisestaqentt pefopren etaeh aes tt Mok beninee cet y#t me ieggeae ein it eviedsieietiary esti opt 15s Mine p alain! fst agg elev sesteraittsirtaued ah HNN MatL 4 vedtienten te Hinrtormaiincenmre me te ausentatot rere anifone nangenlriavanelen Veet Hobo hari vb ad otra shattametenie Hern beret st hit cA Y' { 1bs4 (ooh vetntee nteertgne Tinta Wel ater Stee sherds Sool ok esata tbat tette nde eainriete toe rent Peon sateen ata reat Ba rst hel hii tenn Prt Syle et atte att Hist ebivasenitrs ereee ys Derr eseententy Miler Tet ety Shit hve Beds ty ede Bisel t 19. bi tongen get awe cee oe ve Wil peter Let he eal deiitetilapeitiatyoanttcuéaan tts Cstuicatou unseat titeenstt H settoseserepes teenies Piece ia ythet Bepele vee Wr veal seagtla s4eutioge| i mae roee haved dey #0eicieranad te “0h Chea Jrorhadrt 404 di =i a i haan irre ed 14a emia Weal ennddoy bts Sia Sister cabinet on sun Tite pe ster Series: ; wantin Metieoes iy LW iteten muleesrunstienssl te Seumrivesiuiaiitent tae eteiieces eee eainy odd trot ava MII Pea He liar tthangntt aaa ‘siWEtni at slatee age Sex Wh teatdes pioagis Distr eb ea at vss Si dean Peat iimwetad telus waeceduent raagen: Orayaer treed au S81 in| hen voaeenial oped su boa ry oGaell Mohler Ama sareE ford #4 ( WE ytl Comb Ader t a3 ot anes beet GOR) Lenin c) See ceasd col PinstlRientiedibatiee ne ri i) dations map sand Lg Ne pels sel | oleted age g take t tye $8 pel adhty ode bmg Pehl fay HH Sa tots ol ht eso neeecs eat ah seer Hed Abenatige ry riedes eyed. UR TT aT shai ‘ bord Weetdl tet ane es ( os aa 14 9b bs dived bare } tneseastetiiosteoet Herat et tet teindicrcai ey isd a PHsateanrwers 4 Mapes lice ent y ir o9 Won? Set Di lgangtioaspmsoenytesee, HOH Yoh iaeal eiete tte te ear reg Lip ahibeLee Mie iclin tect man tebies lest Mivot iartem iin) te iaesiiah ry ngnn alice batspiar sed tt otelerediattee ep arts, beaters th resne| HGH HarHid tioeshA = Mami Hee tes sentences naa eh anche hon LAE htt tite Suite 4vatis Civr studs rey th genus eoat Hie wag Teather ciniewel ot hs Hi Fahne wos bed a viet Bde bbb same de ot rel the ons Hebi gmftivegt sate Fen ry MibsteecmeulAlabia hi itt SPE erm eine rHinbentte Ems Gath sega hme akigs Lg Sstadelidteny Creer Hitt dodet ate ceae Heit Saresdisoged hare twit at 4) Ges te Baio Minette a aie bop bats ee ea aie e Phegedh ie! nti ant daamact pagea stat a ) Diitrontrns Menke ees ret desoaitase nt 4 ose -eairy eyial Vohugeha eres ae Hert ty itvndey «ofl Farts ArH 4 aah EIN be Thee ah : ites ere) oles ete MTT eT Mis kbst sniaesl Aiko oh bad dou bias eeate tenastdathad neealtecarte HS espe ie Lander Adah oul Sool aka satchel atogt hes dale nia ‘ acireree Wit shebog ano Ae Aiba ys Keaton 9ar4 ie ohsvgmmtag Wrist raeiiyiotNleortoee ba sitiweel dees nat so saenrenatenisi soqrceeserdehererieaeteh “4 eribateetierid wearin bitty sen Maio aa bait ay WIV21 sihs beh RAdtrel a eusnatheh oes tats 4 Berar eptenagvel tet Fae ie it ses ah 28m petite ibaal bait tn . ptratrante JH ge hee 4 iereay presen Sistinnte ‘ Stone sriaet HoNMiseIve HEN Ab yesh shpfens e400 pureed 700 ’ dene htt to Niel svsiiilat Tiel ae C4 raed agyiid f Hide Mt renidnuiiit ade toeage ys tie lea an ah Hamat oid fei weaned Toten e eeeeaeng ULENTIMPS: enatomateedine pian eestariatsiicrtiteas coset ay z Lassioqesciss jrusnte gear sack 34 aseentsenrimanteetel any sivist debsvittoatanrasecern feat oar se Secrest iyervqaien i tatiana tittint oase) TERT eei tin Heat ay i sateerneeate Ne tebe nantt hia ib srk date th -da Cad ot aft tho eee PPM MNN Cy ata 7] tinaster i cp reahy Toad steeael dey! Eeegss malt say calaetheytin species, teresa rity reenaeatonae ah Anat bahrannd neers st adder phew loan cee 44 resnindarspont ay r Wralfu timtogrwregs te HW ladrananine. bas sayy ‘ Heriteotienne sn oe teh dia ana ll Spt, IE ae beet te id eds Sistas 8 pig Vedtostes Het Se resiemeas vist shepeneiterienayoa Deut dm hoes ree . : ena (Csi sed \iiadodsa emcee Mop ee de ene teas Ih aA vLalionid wk sereen efvaaysancrirrned scousesue@et emeKeUttered eek eal Mterifacpeisrdosisant aeennN ST bite ate inataeelt ee ratio ay Mor Fol shang, aii vbinnosteniven reo onrioaepecseoe Wail et it vemannivaleegyaar iat Hohanaetth sat see OT oR hear gees yuiand at inmaenitalemnstied’ pergola a aces "y ib spesten sisi a adlinidasieig HASH PR TERY OPA Re, RIN hat je preadtoes if He (sti Srnlvanngy y Kean ii fe Raeaeriuipe Pet Bint : ; yet Mh Lactugnganelsots fst A vet tye ite Norerne Ayes \shntace te) ms i ertelennes a ; i Sat clenaben dy Pe st talgatesamatet tty zdiainatese peo) eee raad Cursoesivtemarn taeeertd tareats eoeteben Iie sensu ni100 ot Spa e gh nde WR toa a . tH Vie Donnesheete atete ecg dngedectcineeite aaoyraciepes ete a a amasscnanrnayitt Febye iets PEER AL teat tel yas lata i seasons gnratanesheny Teton ta Hennig tes ayt, ossantat iaand r yet aes 8 fa veaeeat en Ninth ny RANLLE (CAPRI MS Add ATT Tedsat betes ng tvs Henin Ai fe Ege Mec vot: toh tee ied a th ' an ste shia daring sianeyeyonehte ysacte ie hacern tint ttgute dee rot *biwatie stremd shige annpin eMIMEeN eM tee TEse feroedaoeaeet pte teatheti a8 sanetinioedssee hy ap byneah i Mevagisunatehantter nejieem yen Armenia ogden ef Se DP ears vealtedenea a oh We bse lpbsinde bib blbd ve teh OP OYE ae RT: ag caves a barrie reliance caenttehedtiy Hysteeoebteo Te ea rr 4104 Ursa Mesut reaenactuaint ninth arte Hare ree aha Heres SOG MA ost ed Tpit recent tanaaacaiteahiate ye sete harucnviny i 4 aoe rode yar poset geet Terie age ottp et eet fuatvab laity dpe kes abe Cipetesione ay obsde HGH UTED HHH Het coms seeanirpeent| agg ne BG aLEY avert rrieqates taped Moni neqech ater d ener ae basher He nll Naval iy iiteryes pect i iyiteen escent AMtatab Laie hae bWalessiada este tke 5 . by Fe ea popeetent Weyiea teresa NASH id adapt : Lead Hele ay STs eae NINA rogue 16 oo siignwcaresartac oe esabegy va s}eserb nance sao Tavevanteqrore eas , ihoaceprestvenpuacentt aigsstit vee rt (aed stove hess a0 gb Cit Sarr eer se Wriatc wl tuaycpiye te os be ides at broom tn Wears eriacems st oped cadpegre mag PLA HSS IP 9594 4 onthe ote ' i loa inag lon ecane no inh ht et HAMPER Ae vekoLtuertae ayy aa vaeaeneeeatiss wai mtve seeturieacarncnat ony Tageabidcdedstirice att benign Hstnegraterisrapii sant seg ett ctreghrtrser cece rarretanegeuratycaranad toabinn ahs neg easiets Hemet ent tees aninceg potyews Lhe aie es ciel satstraebelscevicg Sie Mimteriaqn og #2 eA prmmmpnwnne (nel Geenit tp UVa ey ott yi RH Amigo Sores Peatan) ae jh eb ies beret dictcashrrotenitanentat es Telli vaiats vendent-anehy pasion ese ier piace t lt 3: Prekiera eitien tet esrb te aah iy tues HHL Maan eet oh oy Pers Sie ey Saatien jeden a WCriNe! ae We, eae = ly tt it i ct priikeh abt Nita eit diving atiok Wat toa Tistaq saeied ol shoale dese packteah dete eahtantesti tnt it Sonat \resNoE tA -HE Hopeandshrggi chin Nee cabal ipekd onelor4ad nob THEA LHOE te to bamel toads hot i EH rete bah, Feet: aah Ohad PNG toed NAbIMe sven on ui aeteT ei ashbeh E48 ASMA Aveo t se sdgee vagtect 9 “I way yi ie ads ans he va vasiledoasg ot erates heer i Henn tt Ant seed eanadcaate ee eegeel nce tA Mintateetent gt 0 MAitoivoutcdseshcreemca tess pRseebrasietaa aeacot tate et 4 H t ebyteeeejaurbncanitis seers wad} Doman od idom eGo eGat nai Heeb Anweted UA iC oi i]s 1¥N ef Haley ariteishovaed (vi dheanoeatooessciond tse suse tesdccret asaaats tana oi ta (iat aanaelaohad anomehoashevan ty aedabamttoe steeds eed Misteit earatere ee . sistibapehoatas seals specail wits vegeta a ; Han att ibe Meseseohisundaatieivert a icier Hansa hl ma edi b ooh oOMTA DI AN ESH Ahan Modbersneiedabeisind ALAMMall Reqs peed, UH myedtt ye Pari ieorasiencise shear tated napahey atin ‘« wah sabes ig sant fetaeeiatir Denti Sayer Tobaeeit vag ieee yititons errant motenegy PUL eines tna? TMH tee it thi tt iene nen nant tena anna ped lebiti rae! VAN LAAPE LOND mn EEpeLeBOhsMel obdlle honed Aah LA ah aden der ered ann eqs gmga Hebel leat, ot On it ocahagtctteaegiten ee ett ipeteri iat ace usenet 24 tala ir " oh Sapte i , vene 18 sh Meitrentaneistatiesnedae ee Toei ttt te ne oanvmrnobae se abe tehihaf etseetags rn) 249" bps yea, tala Kone Arline Sona benedstiste Felt |edaub lots ota Pivertetple! inks wait vam Return this book on or before the Latest Date stamped below. A charge is made on all overdue books. University of Illinois Library | Digitized by the Internet Archive in 2011 with funding from University of Illinois Urbana-Champaign http://www.archive.org/details/phylogenyofhemip16spoo ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME XVI PUBLISHED BY THE UNIVERSITY OF ILLINOIS URBANA, ILLINOIS EDITORIAL COMMITTEE Joun Turovore BuciHo.z FreD WILBUR TANNER Hartey Jones VAN CLEAVE TAREE OF CONTENTS Nos. 1-2. The Turtles of Mlinois. By Arvin Rk. Cann. No. 3. The Phylogeny of the Hemiptera, Based on a Study of the Head Capsule. By CHARLES STOCKMAN SPOONER. No. 4. A Classification of the Larvae and Puparia of the Syrphidae of Illinois, Exclusive of Aquatic Forms. By Exnizarrrn M. Hetss. $4 ILLINOIS BIOLOGICAL MONOGRAPHS Vol. XVI No. 3 PUBLISHED BY THE UNIVERSITY OF ILLINOIS UNDER THE AUSPICES OF THE GRADUATE SCHOOL URBANA, ILLINOIS 1000—4-38—12400 EDITORIAL COMMITTEE Joun THEODORE BUCHHOLZ FRED WILBUR TANNER Harvey JONES VAN CLEAVE UNIVERSITY OF ILLINOIS THE PHYLOGENY OF THE HEMIPTERA BASED ON A STUDY OF THE HEAD CAPSULE WITH 24 PLATES BY CHARLES STOCKMAN SPOONER CONTRIBUTION FROM THE ENTOMOLOGICAL LABORATORIES OF THE UNIVERSITY OF ILLINOIS No. 198 THE UNIVERSITY OF ILLINOIS PRESS URBANA 1938 CONTENTS Introduction Acknowledgments . Materials and Methods The Generalized Hemipterous Head Modifications of the Parts of the Head in Homoptera Phylogeny of the Homoptera The Generalized Heteropterous Head Modifications of the Parts of the Head in Heteroptera Phylogeny of the Heteroptera Summary Bibliography Plates INTRODUCTION The head of the Hemiptera is a highly modified structure. It is not surprising, after comparing it with the head of a generalized, mandi- bulate insect, to find that there has been considerable controversy regard- ing the identity of the various sclerites involved. The problem of the homology of these sclerites was practically hopeless until we obtained some direct evidence from embryology. The early work of Heymons (1899) gave us our first clue. This work was later corroborated and extended by Muir and Kershaw (1911, 1912). Further careful studies of the musculature of the various parts by Muir (1926) and Snodgrass (1921, 1928, 1935) have given us a fairly secure foundation upon which to base comparative studies. Careful and intensive studies of various species have recently been made: Nepa, Hamilton (1931); Naucoris cimicoides, Becker (1929) ; Psylla mali, Weber (1929). Nevertheless the head in various Hemiptera has quite a variable structure, and in many cases superficially similar parts have been misinterpreted. It was with the hope of indicating some of these misinterpretations and thereby gaining some indication of the phylogeny of the group that this study was undertaken. It was thought that a study of the nymphs would aid in the understanding of some of the adult structures, and an effort was made to obtain and study as many nymphal forms as possible. The author is fully aware of the impossibility of showing the true phylogeny by a study of a limited group of characters and of the dangers of misinterpretation involved. There is no intention of claiming finality for the suggestions made. Results will be discussed in relation to the findings of other workers using other sets of characters. The characteristics presented by the head capsule of the Hemiptera appear to be a particularly valuable record for phylogenetic studies because, throughout the order, there has been little modification of func- tion. Hence the structural differences which accompany changes in function are reduced to a minimum. One or two interesting exceptions to this statement will be described later. Very little attention has been paid to the mouth parts in this work because they are pretty much of the same pattern throughout the order. The mandibles and maxillae are discussed as a means of identifying the fixed parts of the head. The types of mandibular levers have been studied to determine their phylogenetic value. The terms applied to the various parts are, so far as possible, those which have been in general use. The general nomenclature of MacGil- livray (1923b) or Snodgrass (1935) has been followed. New terms or new applications of old ones have been suggested for parts previously 8 ILLINOIS BIOLOGICAL MONOGRAPHS incorrectly named or where systematists have applied different terms for the same structure in the two suborders. ACKNOWLEDGMENTS This study was begun under the late Professor A. D. MacGillivray, and the author is greatly indebted to him for help and inspiration. It has been completed under Professor W. P. Hayes, and to him, likewise, the author is indebted for constant help and encouragement. Some of the specimens used in this study were obtained from the collections of the Illinois State Natural History Survey. I am indebted to the late Professor S. A. Forbes and to Dr. T. H. Frison and Dr. H. H. Ross for these courtesies. Among the most interesting of these materials were nymphs of the enicocephalid, Systelloderus biceps (Say) and of the ceratocombid, Ceratocombus vagans McA and Mal. These were loaned through the courtesy of Dr. Ross and, so far as I have been able to dis- cover, are the first nymphs of these families on record. The author has since taken two specimens of the nymphs of Ceratocombus vagans from the University Woods at Urbana, Illinois. The author also wishes to thank Professor H. B. Hungerford for gifts of specimens of Naeogeus burmeisteri L. and S. and Ochterus viridifrons Champ. Mr. H. E. McClure kindly furnished some specimens of Systel- loderus biceps. Mr. Walter Scruggs has spent many hours in arranging and photographing the plates, for which work the author is very grateful. MATERIALS AND METHODS Studies were made of representatives of all of the North American families in which material was available. Nymphs as well as adults were studied in every case in which they were obtainable, and this represents a surprisingly large proportion of the families. The heads were treated in ten per cent caustic potash until they were tairly clear and were then studied under the binocular microscope. It was found that the details were most readily seen in heads that were preserved and studied in glycerine. This had the further advantage of keeping them soft and flexible. The mandibular levers were dissected from heads that had been thoroughly treated in the potash. The larger forms were then cleared in carbolxylol and mounted in balsam, while the smaller forms were studied in a drop of glycerine. The following representatives of the various families were studied. The names are those used in Blatchley’s Heteroptera of Eastern North America (1926), or Britton’s Hemiptera of Connecticut (1923), or VanDuzee’s Catalog of the Hemiptera of North America (1917). PHYLOGENY OF HEMIPTERA—SPOONER 2 HOMOPTERA FULGORIDAE CICADIDAE Otiocerus degerrii Kby. Tibicen sayt (Sm. and Grsb.) adult Otiocerus wolfii Kby. and nymph Amaloptera uhleri VanD. Lamenia vulgaris (Fitch) CICADELLIDAE Cyarda melichari VanD. Acanalonia sp. nymph Acanalonia latifrons (Walk.) Ormenis pruinosa (Say) Pelitropis rotatula VanD. Oliarus vicarius (Walk.) Catonia impunctata (Fitch) Cixius pint Fitch Epiptera sp. nymph Cyrpoptus reineckei VanD. Liberniella ornata (Stal) nymph Pentagramma vittatifrons (Uhl.) adult and nymph Dictyophora florens (Stal) Bruchomorpha sp. adult and nymph CERCOPIDAE Lepyronia quadrangularis (Say) adult and nymph Monecophora bicincta (Say) Agallia constricta VanD. Oncometopia undata (Fabr.) Gypona sp. nymph Jassus olitorius Say adult and nymph Phlepsius excultus (Uhl.) Erythroneura comes (Say) Acinopterus acuminatus VanD. Euscelis bicolor (VanD.) APHIDIDAE Lachnus sp. PSYLLIDAE Pachypsylla celtidis-mamma Riley Trioza tripunctata (Fitch) ALEYRODIDAE Trialeyrodes sp. HETEROPTERA BELOSTOMATIDAE VELIIDAE Belostoma flumineum Say adult and Rhagovelia obesa Uhl. adult and nymph nymph NEPIDAE \IESOVELIIDAE Ranatra americana Mont. adult and Mesovelia bisignata Uhl. nymph Nepa apiculata Uhl. adult and nymph HYDRO METRIDAE NAUCORIDAE Hydrometra martini Kirk Pelocoris femoratus P. deB. adult and N eyniph NAEOGEIDAE N Naeogeus burmeistert L. and S. adult OTONECTIDAE and aeingh Notonecta sp. adult and nymph OCHTERIDAE CorIXIDAE Corixa sp. adult and nymph GERRIDAE Gerris marginatus Say adult and nymph Gerris remigus Say Ochterus americanus (Uhler) adult and nymph Ochterus viridifrons Champ. NERTHRIDAE Gelastocoris sp. adult and nymph 10 ILLINOIS BIOLOGICAL MONOGRAPHS SALDIDAE Lamprocanthia sp. adult and nymph Pentacora sp. ANTHOCORIDAE Triphleps insidiosa (Say) adult and nymph CIMICIDAE Cimex lectularius Linn. adult and nymph REDUVIIDAE Sinea sp. adult and nymph Emesa brevipennis (Say) adult and nymph Melanolestes abdominalis H.-S. NABIDAE Nabis subcoleoptratus Kirby adult and nymph ENICOCEPHALIDAE Systelloderes biceps (Say) adult and nymph CRY PTOSTEM MATIDAE Ceratocombus vagans McA. and M. adult and nymph MIRAE Moris dolobratus (Linn.) adult and nymph Adelphocoris rapidus (Say) LYGAEIDAE Ischnodemus falicus (Say) adult and nymph Mvyodochus serripes Oliv. adult and nymph PyRRHOCORIDAE Euryophthalmus succinctus (Linn.) adult and nymph NEIDIDAE Neides muticus (Say) adult and nymph Jalysus spinosus (Say) CorIZIDAE Corizus sp. adult and nymph Harmoestes reflexulus (Say) Leptocoris trivittatus Say adult and nymph CoREIDAE Anasa tristis (DeG.) adult and nymph Acanthocephala terminalis Dallas ALYDIDAE Alydus sp. adult and nymph PIES MIDAE Piesma cinerea Say ‘TINGITIDAE Corythuca ciliata Say adult and nymph PHY MATIDAE Phymata sp. adult and nymph ARADIDAE Aneurus sp. adult and nymph PENTATOMIDAE Brochymena sp. adult and nymph Euschistus servus (Say) Euschistus servus (Say) variety Euschistus euschistoides (Vollen- hoven) Euschistus tristigmus (Say) Euschistus tristigmus luridus Dallas CYDNIDAE Cyrtomenus mirabilis (Perty) CoRIMELAENIDAE Corimelaena sp. SCUTELLERIDAE Stethaulax marmoratus (Say) THE GENERALIZED HEMIPTEROUS HEAD The generalized head of the Hemiptera would be one which most nearly approaches the head capsule of the mandibulate insects. Since all of the head types of this order are rather far removed from those of any PHYLOGENY OF HEMIPTERA—SPOONER 11 existing mandibulate insect, the designation of a generalized type of head is rather difficult. There are extensive differences between the head structures found in the two suborders Homoptera and Heteroptera. There has been, further- more, some dispute as to which of the suborders is the more primitive. Some workers, who have arranged the orders in an ascending or descend- ing series, assume that the Heteroptera are the more generalized, Com- stock (1915). Others have assumed the opposite and have placed the Homoptera first in their ascending series, Kellogg (1905). Tillyard (1918) states that the Homoptera have retained the more primitive wing form and venation, while the Heteroptera have preserved the more primitive form of head and antenna. Muir (1923) believes that the head of Heteroptera is the more primitive. The earliest fossil forms, however, belong to the Homoptera with the single possible exception of Eugereon described by Handlirsch (1908). Considerable discussion has taken place regarding the affinities of this genus. Tillyard (1921) accepts the decision of Handlirsch that it is a heteropteron while Crampton (1927) expresses his doubt about the matter and gives various reasons for deciding that it is not a heteropteron but is perhaps a forerunner of the Diptera. Judging from the figure reproduced by Crampton in his paper, the writer is inclined to agree with him. If this conclusion is sound, then we are left with the fact that all of the earlier fossil forms are homopterous. The tentorium, as will be shown later, is much more nearly typical in the Homoptera than in the Heteroptera. Certain other features which will be brought out later in this discussion, bear out the fact, that, with one or two exceptions, the head structures of the Homoptera are of a more primitive type than those of the Heteroptera. Only in the form of the labrum in some of the Heteroptera and in the fact that the gular area is not so reduced as in the Homoptera, does the former appear to be the more generalized form. The fossil record, the form and venation of the wings, the condition of the tentorium and other head structures lead the writer to consider that the Homoptera retain more of the ancestral characteristics than do the Heteroptera. We look, therefore, for the most generalized form of head capsule among the former group. Most of the workers on the morphology of the Homoptera have used for their studies one of the cicadas. This is perhaps because of their large size and the availability of material as much as the belief that they represent the generalized type. Most of our knowledge of hemipteran morphology has, indeed, been gained from these studies of the cicadan head, and the structure of other forms has been rather haphazardly compared with that of the cicada. Muir and Kershaw (191la, 1912), 12 ILLINOIS BIOLOGICAL MONOGRAPHS Muir (1926), Snodgrass (1921, 1928, 1935) and Myers (1928) have all made important contributions to the anatomy of this form. A study of the members of the Fulgoridae, in its broad sense, indi- cates to the writer that some of the structures of the heads of members of this tamily show more primitive characteristics than those of any other family of the Homoptera. The author recognizes the fact that this family contains forms which, in many respects, are highly specialized, but he believes, nevertheless, that many of the structures have been retained in rather primitive form. Otiocerus degeerti has been selected to indicate the structures from which the above conclusions have been reached. This species (Figs. 1 and 53) shows the presence of an extensive vertex (Fig. 53, v), a large frons (fr), a distinct postclypeus (pc) separated from the frons by the fronto-clypeal suture (the epistomal suture of Snodgrass 1935), a much smaller anteclypeus (ac) which bears a small pointed labrum (/br) attached to its posterior margin. The maxillary plate (mp) is large and triangular, tapering to a sharp point, the max- illary process. This plate is separated from the clypeus by a deep suture, and it is near the base of this suture that the mandible is attached. This suture is homologous with the genal suture of Muir (1926) and Myers (1928). It marks in reality the lateral limits of the clypeus and, since the manillary plate is made up in part of the gena, this term may well be retained for it. The antafossae (af) are located on the front just dorsad of the fronto-clypeal suture. The antafossae, then, are also just dorsad of the point of attachment of the mandibles and may serve as landmarks to delimit the postclypeus in those forms in which the fronto-clypeal suture is wanting. This relation between the antafossae and the point of mandi- bular attachment has been found to be constant in all of the forms examined. Thus a line drawn across the fronto-clypeal area, slightly ventrad of the antatossae will, approximately, separate the two areas. The lateral margins of the postclypeus are slightly invaginated along the border of the maxillary plate forming the genal suture. The pre- tentorinae occur at the base of these sutures. They are located at the bottom of the infolded area and hence are not visible externally. The anteclypeus is a rather small area with the lateral margins deeply invaginated and the two invaginations, one from each side, meet within the head and form a hollow cylinder which supports the salivary pump and the setae. A long projection extends from the dorso-ventral margin, extending for a considerable distance dorsad into the region covered by the postclypeus (Fig. 346). The complete absence in Otiocerus of those much discussed sclerites, generally designated as the mandibular plates by morphologists and as lorae by systematists, should be noticed. Otiocerus is, in this respect, PHYLOGENY OF HEMIPTERA—SPOONER 13 more primitive than any of the other Homoptera. The gradual develop- ment of these sclerites will be shown later in an interesting series of forms. The mandibular attachment is usually described as being on these sclerites but the evidence here shows that the genal suture is the import- ant feature marking the location of these points. The method of develop- ment of these sclerites shows them to be undoubtedly parts of the clypeus and the writer favors the term paraclypeus for them in place of the terms mandibular plates or lorae. This term has been suggested for them by Crampton (1921) and the areas have been referred to as parts of the clypeus by Deshparde (1933). MODIFICATIONS OF THE PARTS OF THE HEAD IN HOMOPTERA THe VeRTEX.—The vertex is here considered in its morphological concept, that is, as including that portion of the epicranium on each side of the epicranial stem and bounded anteriorly by the epicranial arms. These sutures are termed the coronal and frontal respectively by Snod- grass (1935) but the author sees no reason for changing from the former well known terms. A study of the nymphs gives us an idea of the extent of this area. The epicranial stem and arms are not visible in any adult homopteron known to the author. The term crown has been suggested by Myers (1928) for the dorsal aspect of the head largely because of the incorrect interpretation of the extent of the vertex in the Fulgoridae. Snodgrass (1935) makes this same error but retains the term vertex and states that this area in the Homoptera, particularly in the Fulgoridae, is a very large area and that these forms, in consequence, have a greatly reduced frons. He further states that the peculiar enlargements of the head, so often found in members of this family, are formed entirely by the enlargement of the vertex. A study of the nymphs of these forms indicates that this conclu- sion is incorrect. These forms, in general, have the vertex limited largely, if not entirely, to the dorsal aspect of the head, and the cephalic aspect of the head contains an extensive frons (Figs. 11, 40, and 41). The pro- cesses on the heads of these insects are then made up of extensions of both vertex and frons. This is true of Scolops sp. whose nymphs show a very long epicranial stem extending to the apex of the elongation, then dividing into the two epicranial arms which extend down the cephalic surface of the elongation and mark the position of the frontal carinae in the mature insect. In some families of the Homoptera the vertex is rather extensive and the frons is reduced to a very small area (Fig. 23). Snodgrass (1935) figures the head of Oecleus borealis and labels the carinae surrounding the median ocellus as the epicranial arms, and, con- sequently, the minute area included by them, as the frons. The study of 14 ILLINOIS BIOLOGICAL MONOGRAPHS a cixiid nymph, which the writer succeeded in obtaining only after the plates for this article were made up (and hence it is not figured), shows a rather short epicranial stem with the arms branching out just caudad of the compound eyes, and curving cephalad, paralleling the inner margins ot these eyes. Hence the frons is a rather extensive area in these forms. Compare the figure of the nymph of Epiptera sp. (Figs. 36 and 63). This is a closely related form. Reference to figures of the following species will give some idea ot the relative extent of the vertex and frons in the various forms. The epicranial stem is comparatively long in such nymphs as the delphacids, Liburmiella ornata ( Fig. 38, es) and Pentagramma vittatifrons (Fig. 39), as well as in the cicadid, Tibicen sayi (Fig. 44) ; the membracid, Ceresa sp. (Figs. 24 and 25) ; the cicadellids, Jassus olitorius (Fig. 47) ; Gypona sp. (Fig. 48); the aphidid, Lachnus sp. (Fig. 50); and in the psyllids, Pachypsylla celtidis-mamma (Fig. 51) and Triosa tripunctata (Fig. 52). It is only moderately long in the cercopid, Lepyronia quadrangularis ( Fig. 42) and is very short in such forms as Bruchomorpha sp. (Fig. 40) and in Acanalonia sp. ( Fig. 37). THe Frons.—That area of the head capsule bounded dorsally and sometimes laterally by the epicranial arms and ventrally by the fronto- clypeal suture is considered as the frons. Referring to the remarks made in the discussion of the vertex, we find that this area also varies greatly in size and is not always the greatly reduced sclerite suggested by Snodgrass (1935). As was stated in the description of Otiocerus degeerii, the fronto-clypeal suture is wanting in many forms and in these we may use the imaginary line drawn across just ventrad of the antafossae as the ventral limit of the frons. The frons is very extensive in many of the fulgorids, such as Otiocerus degeertt (Fig. 1, fr); Lamenia sp. (Fig. -2); Amaloptera uhleri (Fig. 3); Cyarda melichari (Fig. 4); Ormenis pruinosa (Fig. 6): Pelitropis rotatula (Fig. 7); Dictyophora florens (Fig. 15); and Acana- lonia latifrons (Fig. 18). It is of moderate size in the cercopid, Lepy- ronia quadrangularis (Fig. 20) and the cicadellids, Oncometopia undata (Figs. 28 and 49); Jassus olitortus (Figs. 29 and 30); Acinopterus acuminatus (Fig. 32); and Erythroneura comes (Fig. 31). The frons 1s much reduced in the aphidid, Lachnus sp. (Fig. 50) and the psyllids, Pachypsylla celtidis-mamma (Figs. 34 and 51) and Trioza tripunctata (Fig. 52). In the cicadid, Tibicen sayi (Figs. 22, 23, and 44), the mem- bracid, Ceresa sp. (Figs. 24 and 25), and the cercopid, Monecophora bicincta (Fig. 21), the frons is reduced to an extremely small area. It is well to call especial attention, here, to the marked difference in the size of the frons in the two cercopids, Lepyronia quadrangularis ( Fig. 19) and Monecophora bicincta (Fig. 21). PHYLOGENY OF HEMIPTERA—SPOONER 15 Tue CrypeaLt ReGion.—This region always consists, in the Homop- tera, of at least two parts, and in the great majority of forms, of four parts. The statement made by Snodgrass (1935) that in some species of Fulgoridae, the clypeus consists of a single piece is incorrect. He cites Oecleus borealis as an example. The division between the anteclypeus and postclypeus is, in this form, obscured by a strongly elevated carina ex- tending vertically down the frons and clypeal region. The lateral aspect of this region, however, shows a clear separation between the two areas and this division is still more readily seen in specimens that have been treated in caustic potash. The paraclypeus is also present in this form. The anteclypeus and postclypeus are always present in the Homoptera, and in the majority of forms there is a more or less well developed paraclypeus on each side. This divided condition of the clypeus is commonly found in some of the lower insects, such as the Orthoptera. Crampton (1921) refers to these areas as the postclypeus and the anteclypeus. He also describes the lateral areas of this region as found in the larva of Corydalis and applies the term paraclypeus to them. These areas were termed the antecoxal piece of the mandible by Comstock (1925) and the clypealia by Mac- Gillivray (1923b). Crampton (1921) suggests that, in these insects, these areas are formed by the extension of the epicranial arms across the clypeus. This is not the method of their formation in the Hemiptera, and they can therefore not be homologous structures, but the writer has used the term paraclypeus to designate them. The postclypeus (fc) is usually a large and well defined area. It furnishes the attachment plane, internally, for the muscles of the pharyngeal pump. In many forms it is distinctly separated from the frons by the fronto-clypeal suture, as in Otiocerus degeerti (Fig. 1) ; Catonia impunctata (Fig. 9) and Tibicen sayi (Fig. 23). This suture is wanting in the cercopid, Lepyronia quadrangularis (Fig. 20), the mem- bracid, Carynota mera (Fig. 26) and in all of the cicadellids (Figs. 27-32). The position of the antafossae (af) gives us the clue to the extent of the paraclypeus in these forms. The places of attachment of the pharyngeal muscles also aids in locating its anterior limits. The greatly reduced frons in the cicada and the enormous enlarge- ment of the postclypeus has resulted in a great deal of discussion as to the homology of these parts. Vickery (1908) called the postclypeus the clypeus, Meek (1903) labelled it the frons, while Berlesi (1909) recog- nized two areas and called them postfrons and frons. Muir and Kershaw (1911) returned to the term clypeus, Branch (1914) recognized it as the frons as did Snodgrass (1921) and Muir (1926). The latter suggested that it might be a clypeofrons. Snodgrass (1921) demonstrated, by a study of the muscle attachments that it was clearly clypeal in nature and 16 ILLINOIS BIOLOGICAL MONOGRAPHS termed it the postclypeus. Myers (1928), however, still refers to it as the frons. The postclypeus, in those forms which lack the paraclypeus, is bounded laterally by the genal sutures. These margins are somewhat invaginated and from the ventral portions of these invaginations, wing- like projections extend to the pharyngeal pump which they help to support. Where the paraclypeus is well developed, the anteclypeus is marked off by a deeply invaginated suture on each side. These are the frontal sutures of Muir (1926), Myers (1928) and Snodgrass (1935). They are not extensions of the epicranial arms, as will be shown later, and hence should hardly be termed the frontal sutures. The invaginations along these sutures form a deep flange about the postclypeus, extending into the head, which serves for muscle attachment and from the ventral margins of which there extend wing-like supports to the pharyngeal pump. The anteclypeus (ac) is a small but well defined area attached to the ventral margin of the postclypeus. The lateral margins are more or less invaginated and sclerotized, ranging from the strongly sclerotized cylinder of Otiocerus wolfi (Fig. 346) to the nearly membranous and flattened areas found in cicada. These invaginations serve as supports for the salivary pump and for the mesal margins of the mandibular and maxillary setae. The paraclypeal regions make up the areas which have occasioned the greatest discussion of any part of the hemipterous head. They have been called the lorae by systematists for many years. Smith (1892), in dis- cussing the morphology of the cicada, stated that they were derived from the mandibular segment and hence referred to them as the mandibular plates. Muir and Kershaw (191la) described these areas as extensions of the clypeus, and the same authors (1912) stated that they were not formed from the mandibular sclerite and had no relation to the mandibles. They declared them to be homologous with the gena of other orders. Muir (1926) declared them to represent a part of the genal area. He states, in this same work, that there is no embryological evidence that they are parts of the mandibular segments. Snodgrass (1927) agreed with this conclusion but later (1935) again refers to them as the mandibular plates. Myers (1928) homologizes them with the gena and states that they are not lateral clypeal sclerites nor mandibular plates; Weber (1929) calls them the laminae mandibulare, while Deshparde (1933) refers to them as clypeal sclerites. Examination of the drawings of the head of Otiocerus degeerii (Fig. 1) and of Lamenia sp. (Fig. 2) shows that the paraclypeal areas are wanting. The anteclypeus is attached, with a very slight indentation, to PHYLOGENY OF HEMIPTERA—SPOONER 17 the ventral margin of the postclypeus. The drawing of Amaloptera uhleri (Fig. 3) shows the anteclypeus included for a considerable distance within the postclypeus, cutting off a small area on each side which may be regarded as the beginning of the paraclypeus (Fig. 3, pac). A study of a series of forms such as Cyarda mielichari (Fig. 4), Acanalonia latifrons (Fig. 18), Pelitropis rotatula (Fig. 7), Epiptera sp. (Fig. 11), and Bruchomorpha sp. (Fig. 16) shows in the order named progressive steps in the inclusion of the paraclypeus by the postclypeus and hence the increasing size of the paraclypeal areas. Muir and Kershaw (1912) state that the embryonic development of the Hemiptera shows there is an extension or overgrowth of the areas referred to by them as the genae and the manillary plates. This satis- factorily explains the conditions found in such forms as the cercopid, Lepyronia quadrangularis (Fig. 20), the membracid, Carynota mera (Fig. 26) and others in which the distal ends of these areas extend well beyond the point of union between the postclypeus and the anteclypeus. The paraclypeal areas in some forms have become entirely vertical and are visible only from the lateral aspect, as in Catonia impunctata (Figs. 9 and 61). The study of this series leaves little doubt that the paraclypeal areas are actually portions of the clypeal area cut off by the progressive devel- opment of a suture extending from each proximal corner of the ante- clypeus. This suture is the one referred to by Muir (1926) as the frontal suture. Tue MAaxiILiary PLates.—The origin of these plates (mp) from a part of maxillae in the embryo was first described by Heymons (1899) and corroborated by Muir and Kershaw (1911 and 1912). The termin- ology of these plates has since been quite uniform. MacGillivray (1923b) refers to them as the hemimaxillae. These areas, in addition to a portion of the maxillae, undoubtedly include, at least in part, the genae and postgenae. Snodgrass (1921) makes the statement that they are largely postgenae. There are traces of sutures, in some forms, which may indicate the line of fusion of the maxillary area with the postgenae. These sutures have been termed the maxillary sutures by Muir (1926). They are very faint and have been indicated by dotted lines in the drawings of Euscelis bicolor ( Fig. 82) and of AMlonecophora bicincta ( Fig. 71). Muir (1926) also recognizes a fourth suture, the labial suture, along which the invaginations (metatentorina of MacGillivray 1923b) of the metatentoria occur. The writer has not been able to find these sutures in the forms studied. They may be the line of attachment of the labial membrane to the postgenae or they may represent the postoccipital sutures of Snodgrass (1935). 18 ILLINOIS BIOLOGICAL MONOGRAPHS The maxillary plates form most of the lateral and caudal aspects of the head. They enclose the maxillary and mandibular setae and lend support to them. They become narrower ventrally and end in a sharp point which has been termed the maxillary process. These processes support the labium, especially when the insect is in the act of feeding. The maxillary plates vary greatly in size and shape throughout the group. (Figs. 53-86, mp). THe Lasrum.—This is a small, narrow, triangular sclerite attached to the ventral margin of the anteclypeus. It lies along the base of the groove of the labium, partially covering this groove and lending support to the mandibular and maxillary setae. It varies somewhat in length but is otherwise quite uniform in the Homoptera. There has been some discussion in regard to the composition of this sclerite. It has frequently been referred to as the epipharynx (Crawford 1914). Muir and Kershaw (1911a) state that “The division between the labrum and the epipharynx is obscure” and suggest the term labrum- epipharynx for it. MacGillivray (1923b) and Myers (1928) follow this terminology. Snodgrass (1935) calls it the labrum. The epipharynx, in mandibulate insects, is the inner surface of the labrum. In certain sucking insects, as the Diptera, there is evidence of a projecting outgrowth of this inner lining which is visible externally and which may be differentiated from the labrum. There is no such evidence in the Homoptera and, hence, there is no more reason for referring to this sclerite as the labrum-epipharynx in the Homoptera than there is in the mandibulate insect. Tue CaupaL Aspect oF THE Heap.—This area of the head in the Homoptera is almost entirely membranous. The lateral and ventral borders of the large occipital foramen (oc) are formed by the occiput which is fused with the vertex without evidence of a suture. The postoccipital area is membranous, and it is very difficult or impos- sible to determine the exact division between it and the neck membrane. Odontoidea are seldom distinguishable. Their position is indicated by the occurrence of the metatentorinae (Fig. 91, mt). The metatentorinae are externally visible in very few species. There is no gula or gular area in this suborder. The labium is joined to the maxillary plates by membrane. Tue TentoriuM.—The tentorium of the Homoptera is very nearly typical. A good deal of discussion has occurred in regard to this struc- ture, and the fact that some secondary structures occur has resulted in some confusion. Muir (1929) states that the anterior arms of the tentorium are invaginated from the hypopharynx and hence cannot be homologized with those of other insects nor should they be used as land- marks of the fronto-clypeal suture. He further states that this is similar PHYLOGENY OF HEMIPTERA—SPOONER 19 to conditions found in the Myriapoda and the Apterygota and hence indicates a more primitive origin than was previously supposed for the Hemiptera. The author does not understand just what Muir has in mind and does not agree with the conclusions. Snodgrass (1928) points out the homology of the tentorium of all insects with the hypopharyngeal apophyses of the Myriapoda but states that the “final condition is characteristic of all Pterygota except the Ephemerida and Odonata.” This of course implies the homology of the tentorium ot the Hemiptera with that of the mandibulate insects. The tentorium of the members of the Cercopidae appears to be the most nearly typical of any of the Homoptera. The metatentoria (posterior arms) are invaginated from the membrane, on each side, about at the middle of the occipital foramen (Figs. 100 and 102, mt). These metaten- torinae supposedly mark the position of the post-occipital suture and of the odontoideae, but neither of these structures are distinguishable in these forms. The metatentoria extend mesad and unite to form the corpotentorium (body of the tentorium). This appears as a narrow, cylindrical bar, extending across the occipital foramen (Fig. 102, ct). A broad, heavily sclerotized plate extends ventrad from each corner of the corpotentorium. The plates merge with the evaginations of the hypopharynx. These wings of the hypopharynx are perhaps the “invagination of the hypo- pharynx” referred to by Muir (1929). They are clearly secondary in nature and have become united with the tentorium proper during the evolution of the group. They serve as supports for the pharyngeal pump and as guides for the maxillary and mandibular stylets. Two narrow rods may be observed extending dorsad, one from each side of the meson of the corpotentorium. Near the cephalic ends of these rods each divides into two branches. The branch nearest the meson extends to a point at the base of the genal suture, ventrad of the anta- fossae where may be found the opening of the invagination which is a pretentorina. The rods in question represent the pretentoria (Fig. 102, pt). The lateral branch, extending cephalo-laterad from each _pre- tentorium, probably represents the supratentorium (the dorsal arms) (Fig. 102, st). This branch extends forward until it comes in contact with the head capsule where it may become lightly attached. There are no external signs of invagination on the head, for these structures and their position agrees with the account of the supratentorium given by Riley (1904). This author states that the supratentorium in Blatta appears as an outgrowth from the pretentorium and that they are not independently invaginated. Nelson (1915) corroborates these findings in the honey bee, 4 fis. The tentorium in Lepyronia (Figs. 101 and 102) and in Monecophora (Fig. 100) consists of all of the parts found in the head of generalized 20 ILLINOIS BIOLOGICAL MONOGRAPHS insects and they are formed in the normal manner. There are two pairs of invaginations, the pretentorina and the metatentorina, which occur in relatively the same positions and serve as landmarks for the same sclerites as they do in the mandibulate insects. The head of the cicadid, Tibicen sayi (Figs. 104 and 105), has the same type of tentorium except for the lack of the supratentoria. The Fulgoridae also lack the supratentoria, and there is a great variation in the degree of sclerotization of the pretentoria (Figs. 87-95). Many of these are so lightly sclerotized at the cephalic ends as to be easily pulled free from the head, and one may mistakenly consider them to have been entirely free from the head capsule. The Membracidae have a somewhat reduced tentorium. There is no evidence of the pretentorial arms in Ceresa sp. ( Figs. 106 and 107) nor in Carynota mera (Fig. 103). In the latter species, the dorsally projecting point at each end of the corpotentorium might be considered a remnant of the pretentorium, but it is not in the normal position and it is difficult to conceive of the structure surviving at the point farthest from the place of invagination. The tentorium of these forms is otherwise similar to that found in the Cicadidae. The loss of the pretentorium may have accompanied the decided deflection of the head, so that the anta- fossae are located directly beneath the corpotentorium when the head is in its normal position. Another unusual condition is found in the tentorium of the Cicadel- lidae. In these forms, the metatentorium and corpotentorium are similar to those described in the preceding families. There are, however, no pre- tentorial arms attached to the corpotentorium. There does occur, just ventrad of each antafossa, an extensive apodeme which extends dorsad and ends without attachment of the distal end to the head capsule. These apodemes, in Jassus olitorius (Figs. 109 and 110, ap) and in Acinopterus acununatus (Fig. 111, ap), are long and straight. They are branched in Euscelis bicolor (Fig. 112), Phlepsius excultus (Fig. 113), and Oncometopia undata (Fig. 114). Notice that this branching occurs well toward the distal end of the apodeme in the first two species, while in Oncometopia it occurs almost at the point of invagination. The author was unable to find any trace of these apodemes in Erythroneura comes (Fig. 115). The homology of these apodemes is in doubt. One is tempted to refer to them as the pretentoria. They originate at the place at which the pretentorina generally occurs. If they are homologous with the pre- tentoria then the branches would be the supratentoria. The author has not found any reference to pretentoria which do not connect with the corpotentorium. They have, therefore, been referred to simply as apo- PHYLOGENY OF HEMIPTERA—SPOONER 21 demes in this work. Embryological studies or the examination of a large range of species might throw some light upon this problem. The psyllid, Pachypsylla celtidis-mamma, possesses a tentorium which resembles in form that of the cicada. It differs in the fact that the corpotentorium is shorter and that the pretentorial arms are heavier and more firmly united with the head capsule. The aphid, Lachnus sp., like- wise resembles the cicada in the structure of the tentorium, excepting that the pretentorial arms extend from the corpotentorium at such an angle that they are hidden by the corpotentorium when the head is examined from the caudal aspect. It is of interest, here, to consider the family Peloridiidae. This is a small family of subantarctic Hemiptera about which there has been much discussion as to its systematic position. It was placed in the Heteroptera originally and Kirkaldy (1906b) included the species in the family Ochteridae. China (1924) suggests that it form a new suborder between the Homoptera and Heteroptera. Myers and China (1929) made a thorough study of the external anatomy of Hemuodoecus leat and conclude that the family belongs to the Homoptera and that “‘it is very near the ancestral stock of the two suborders.” A study of their figures shows that the tentorium in this species is typically homopterous and is quite similar to that of some of the Fulgoridae. Tue Lastum.—Very little attention has been paid to the labium in this study. The pattern, throughout the suborder, is quite uniform. Myers (1928) states that the labium consists of three segments with signs of a fourth. The vast majority of forms possess an apparently three- segmented labium. Oestlund (1918) describes a five-segmented labium for the tribe Lachnini of the Aphididae and considers this condition to be the primitive one for the family. Vickery (1908) figures this type of labium. A six-segmented labium was described for the tropical ful- gorid, Pyrops candelaria, by Kershaw (1910). The labium in the Homoptera is attached apparently directly to the neck membrane just behind the ventral corners of the maxillary plates. Tse ManpispuLtar Levers.—The mandibular stylets, in the Homop- tera, are attached to the head capsule by means of a sclerotized plate which is formed by invagination of the upper end of the genal suture and known as the mandibular lever. One end of this lever is attached to the head near the end of the genal suture, just ventrad of the antafossae. The distal end of the lever is attached to the end of the mandibular stylet. A simple type of this lever is seen in Ottocerus degeerit (Fig. 350, 1). The lever in this species joins the mandibular stylet at an acute angle (Fig. 350a, 7). The shape of the head influences the length of the lever and the angle at which it joins the mandibular stylet. 22 ILLINOIS BIOLOGICAL MONOGRAPHS The cicadid, Tibicen sayi (Fig. 352), shows a form in which the base of the mandibular stylet is forked. One fork uniting with the lever (1), the second fork extending dorsally into the head and giving attachment to the retractor muscles which arise on the dorsal wall of the head. This forked condition of the base of the mandibular stylet is also seen in the cercopid, Lepyronia quadrangularis (Fig. 351). In this form, the inner fork seems to connect with the base of the maxilla as well as with the retractor muscles. The inner fork is much reduced in Oncome- topia undata (Fig. 353), being little more than a tendon attaching the retractor muscles. The lever in this species is bent, forming almost a right angle. The author found no evidence of a mandibular lever in Pachypsylla celtidis-mamma. Weber (1929) states that it is absent in Psylla mali. The lever, then, may be characteristically wanting in the Psyllidae. Tue MaxiLiary Lrver.—The maxillary stylet of the cicada is also attached to the head capsule by means of a lever which is more nearly like the mandibular levers of the Heteroptera than are those of the mandibles of the Homoptera. This structure has not been studied in the other families of the Homoptera. It is lacking in the Heteroptera. The place of attachment of the maxillae varies considerably in the different forms; hence they cannot well be used as landmarks for the head sclerites and, therefore, they have been omitted from this work. PHYLOGENY OF THE HOMOPTERA These studies on the head capsule have brought to light a number of points which may be of significance in a study of the phylogeny of the group. A brief summary of the present classification may be of service. The Homoptera was first divided into the series Auchenorhyncha and Sternorhyncha by Amyot and Serville (1843). Duméril (1806) had already proposed the term Auchenorhyncha. These series were based upon the position of the mouth parts and are still in good standing. The families recognized as belonging to the Auchenorhyncha, arranged in a generally accepted ascending order are, the Cicadidae, Cercopidae, Membracidae, Fulgoridae, and Cicadellidae. A few years ago there was a tendency among students of these insects to break up the Fulgoridae and Cicadellidae into a number of families. Recent workers, however, have returned to the older classification and Britton (1923) lists the five families given above. European workers, Muir (1923), still split the Fulgoridae into some fourteen families. The Sternorhyncha is composed of the families Psyllidae, Aphididae, Aleyrodidae, and Coccidae. Few changes have been made in this arrange- ment through the years. Each family forms a distinct and rather homo- geneous group. PHYLOGENY OF HEMIPTERA—SPOONER 23 The author has already stated that he considers the Fulgoridae to have retained some of the most primitive conditions in the structure of the head capsule. It should be emphasized that this family represents quite a varied assortment of insects, many of them highly specialized in certain respects. The splitting of this group into numerous families is probably justified but should await careful morphological studies of representatives of the group from all over the world. Most workers have considered the Cicadidae as most primitive, while Myers and China (1929) suggest the recently discovered family, Pelori- diidae, as representing the most primitive living forms. The author has not seen specimens of this family and cannot express an opinion upon it. Muir (1923) states that “some writers derive the Psyllidae from a psocid-like ancestor and so we must consider all the other Homoptera and Heteroptera as derived from the Psyllidae. In my opinion this is a reverse of the truth.” The same author in his diagram of the affinities of the Homoptera, derives the Fulgoridae very early from his Protohomoptera—in fact it is the first branch to leave the main homopteran stem. The developmental series of the paraclypeal areas described in the Fulgoridae indicates a very primitive condition in some of these forms. Certain structural resemblances to the Heteroptera, which will be dis- cussed in detail later, add evidence for this conclusion. We find, on comparison of the heads of Tibicen sayi (Figs. 23 and 72), Oncometopia undata (Figs. 28 and 79), and Monecophora bicincta (Figs. 21 and 71) a striking similarity in form and structure. All three of these species agree in having a greatly reduced frons and an enor- mously enlarged postclypeus. MJonecophora differs markedly in this respect from Lepyronia quadrangularis (Figs. 19, 20, 69, and 70). Oncometopia, on the other hand, differs in the same degree from the other members of the Cicadellidae studied (Figs. 27, 29, 30, 31, 32, 77, 80, 81, 82, 83, and 84). These facts indicate that perhaps the group represented by Oncome- topia was derived from the subfamily Cercopinae of the Cercopidae, which includes Monecophora, while the other members of the Cicadel- lidae arose from the subfamily Aphrophorinae, which includes Lepyronia. These forms would then represent two distinct families. Oncometopia and its allies has, at times in the past, been separated from the Cicadel- lidae, placed in a separate family, and known under different names. The name Tettigonidae was applied to this group by Uhler (1875) and Tettigoniellidae by Melichar (1905). Recent writers have reduced this group to subfamily rank. The adult aleyrodid (Fig. 35) shows closer relationships to some of the Cicadellidae than to the Psyllidae or Aphididae, as far as head 24 ILLINOIS BIOLOGICAL MONOGRAPHS structure is concerned. The latter two groups, characterized by lack of sclerotization of considerable areas of the head capsule, are, thereby, sharply separated from the rest of the Homoptera. Other characters must be considered to obtain any ideas of relationships in the Sternor- hyncha. Weber (1929) has discussed these at some length but leaves the question still open. Kershaw and Muir (1922) studied the genitalia of the Auchenor- hyncha and recognized three types of male genitalia: (1) the cercopid type found also in the Membracidae and Cicadellidae, (2) the cicadid type, and (3) the Fulgoroidea type. The last section they further divided into three groups, all developments of the cercopid type. This evidence tends to show the primitive character of the Cercopidae which is also borne out by the present study of the tentorium. The thoracic sclerites were studied by Taylor (1918). He grouped the Cicadidae and Cicadellidae with the Aphididae and Psyllidae as having similar thoracic structures. The Membracidae stand alone with a specialized prothorax and the Cercopidae, Fulgoridae, and Aleyrodidae are grouped together because of similarly fused metathoracic sclerites. Two superfamilies of the Auchenorhyncha were recognized by Muir (1923): the Cicadoidea, which possessed antennae with very few sense organs on the flagellum, and the Fulgoroidea, whose antenna possessed many such organs. The structure of the ovipositor, as pointed out in this same paper, overlaps these antennal characters somewhat. He further states that the Cixiidae, considered as a subfamily of the Fulgoridae in this work, possesses the most normal and primitive wing venation of any recent homopteron. Kirkaldy (1906a) uses the method of oviposition as a basis of dividing the group. He cites the fact that the insects of the Poekillopter- idae and Issidae, here recognized as subfamilies of the Fulgoridae, deposit their eggs externally while the Cicadidae, Cercopidae, Cicadellidae, Membracidae, and in part the Fulgoridae deposit them more or less internally. This, perhaps, is further evidence of the primitive position of some of the Fulgoridae. These attempts at unravelling the evolution of the Homoptera are all the writer has been able to find. They show that we are still a long way from the end of the road. The accompanying diagram (Text-figure 1) gives an idea of the conclusions regarding the relationships of the families arrived at by a study of the head capsule. THE GENERALIZED HETEROPTEROUS HEAD The problem of selecting a generalized type of head structure for the Heteroptera is beset with the same difficulties found in the study of the PHYLOGENY OF HEMIPTERA—SPOONER 25 Homoptera. There is a high degree of specialization in all of the forms, and hence considerable difhculty is experienced in selecting characters which might show progressive development. The outstanding difference in head structure between the Homoptera and the Heteroptera is in the presence of an extensive gular area in the latter group. Students who accept the fossil form Eugereon as a primitive heteropteron (Tillyard, 1921) consider that the mouth opening in this group was originally di- rected cephalad. Consequently the ventral direction of the mouth opening 3 3 8 iF) wy v v Ay 5 is] = s a= pd o v Dv 0 us «COS Ps = < iS) a] uv ~] ~ v aad pad 9 u < vU Cf So 8 SS 5 aoe. So «3 & BS tie § Peek wa FS = iS 9 5 Xx S <4 ot s 0. = oOo a 8 o~ o Ss YoY oO SS o jor oo = Gy S&S 2 2 GS or Qo Ko a i) - Oo $9) OL a \ \ - Cercopidae Frotohete rop terat-Proto homop tera é Protohe mip tera TEXT-FIGURE 1 becomes a specialized character. No consistent series can be based on this character. It seems to be correlated with feeding habits, the predaceous forms having the more nearly cephalic mouth opening. Assuming that the Heteroptera originated from a stock common to the Homoptera or as an offshot of the Homoptera, we would expect the size of the gular area to indicate relationships. The shorter the gular area, the more primitive the head structure would be. Here again we find difficulty in arranging the existing forms in any logical series based on this character. Ekblom (1926) considers the Saldidae as representing the most prim- itive of living Heteroptera. He bases his conclusions on the short gular area, the ventrally directed mouth, and what he terms the primitive feed- 26 ILLINOIS BIOLOGICAL MONOGRAPHS ing habits, primitive habitat, and methods of egg laying. The writer agrees that the Saldidae are comparatively primitive in head structure and are near the generalized type but he cannot agree with the reasons advanced by Ekblom. Surely the habit of probing the sand for food is not a primitive method of obtaining food nor is the shore line a primitive habitat for insects. Most students consider that insects were originally terrestrial animals and that the present day aquatic and semi-aquatic species are specialized from terrestrial forms and are not generalized forms on the way to a land environment. A comparative study of the head capsule of the various families of Heteroptera has lead the writer to select two external structures as a guide in selecting the primitive forms and arranging the families in a series. An internal character bears out his conclusions in some cases. Other characters are needed to further subdivide the group. Based upon the study of the Homoptera in which we considered the lack of the paraclypeal areas as a primitive condition, the form of these areas in the Heteroptera is taken as an excellent character which can be used to show successive steps of modification. The second character used in grouping the various families is found in the form of the labrum. This structure, in some species is broad and flap-like (Figs. 152, 155, and 157). It is very similar to that found in most mandibulate insects. This is con- sidered as a generalized form, and the progressive changes to the long slender triangle found in many forms (Figs. 177 and 179) indicates specialization. Cimex lectularius (Figs. 152, 154, and 237) shows the most primitive combination of these two characters. Objections may be made to the con- sideration of a parasitic form as a typical or generalized type. However, the writer believes that Cimex is a primitive form rather than a degener- ate one. Notice the eyes which consist of a scattered group of ocelli. Surely this is a primitive condition. We could consider the loss of the compound eyes as a retrogression accompanying the parasitic habit but we hardly look for a return to the primitive scattered ocelli as such a process. This is certainly the retention of a primitive condition. The writer, however, does not insist too strongly on the acceptance of this form as the most primitive one in the Heteroptera. The members of the family Anthocoridae have equally generalized characteristics, and Triphleps insidiosa has been chosen for the description of these primitive characters. (Figs. 158, 239, and 240). The saldid, Lamprocanthia sp. also very closely approaches this form in simplicity (Figs. 156 and 238), but for reasons which will be considered later the writer prefers the anthocorid as the most generalized type. Both of these forms show the small paraclypeal areas and the broad, flap-like labrum which have been taken to represent the least specialized condition found in this suborder. PHYLOGENY OF HEMIPTERA—SPOONER 27 A description of the head capsule of Triphleps insidiosa (Figs. 157, 158, 239, and 240) is given as the generalized type. The epicranial stem and arms are distinct in the nymph (Fig. 157, es, ea). Each arm extends laterad to the compound eye and parallels the mesal margin of the eye for at least half the length of the eye. These sutures divide the vertex from the frons and mark the caudal limit of the frons as approximately in line with the caudal margins of the compound eyes. The fronto-clypeal suture is not present, and this fact leaves some doubt as to the exact extent of the frons. The attachments of the mandib- ular stylets are located, as they are in the Homoptera, near the ends of the genal sutures just below the antafossae. The line between these points, marking the position of the fronto-clypeal suture, must be arched caudad in Triphleps so as to miss the anteclypeus. Just how great this arching is is difficult to say, and it is possible that in some forms the postclypeus has been entirely cut into two lateral areas by the retreat of the so-called frontal sutures. The anteclypeus (ac) is a rather narrow area extending cephalad from the postclypeus. Its lateral margins are deeply invaginated. This area is called the tylus by systematists. There is no suture between the postclypeus and the anteclypeus in Triphleps. The paraclypeal areas (pac), termed the jugae by systematists, ex- tend, one on each side of the anteclypeus, for about one-half the length of the anteclypeus. The cephalic half of the anteclypeus is bounded on each side by a maxillary plate (mp). The labrum (/br) is a broad, flap-like sclerite attached to the cephalic end of the anteclypeus. The lateral and ventral aspects of the head are formed by a solid sclerotized area without sign of sutures. This area is made up of the manillary plates, the genae, postgenae, and a sclerotized gular area. There are no landmarks present to indicate the extent of any of these parts. MODIFICATIONS OF THE PARTS OF THE HEAD IN HETEROPTERA THe VERTEX.—The size of this area varies considerably with the shape of the head. The epicranial arms are visible in all of the nymphs examined. The epicranial stem varies from very long in Sinea sp. (Fig. 160) to very short in such forms as Gerris marginatus (Fig. 136), Pelo- coris femoratus (Fig. 125), and Corixa sp. (Fig. 133). It is entirely wanting in Aneurus sp. (Fig. 206) and Brochymena sp. (Fig. 208). The epicranial arms branch out at some point caudad of the cephalic margins of the compound eyes, usually near the posterior margin as in Sinea sp. (Fig. 160, ea), Nabis subcoleoptratus (Fig. 165) and Euryophthalmus Succinctus (Fig. 178). The branching occurs further cephalad in Emesa 28 ILLINOIS BIOLOGICAL MONOGRAPHS brevipenmis (Fig. 162). The vertex is rather extensive in these forms, but in Cimex lectularius (Fig. 153) and Ischnodemus falicus (Fig. 175) the arms branch well behind the eyes and the vertex is much reduced. The vertex is limited to the lateral portions of the head capsule in dneurus sp. (Fig. 206) and Brochymena sp. ( Fig. 208). The shape of the head seems to control this character, and it varies frequently within the limits of a single family. Tue Frons.—This area varies inversely with the variation of the vertex described in the preceding section. Those forms with a large vertex have a comparatively short frons. The area also varies with the position of the postclypeus. The fronto-clypeal suture is never present in the Heteroptera. The antafossae serve as landmarks to locate this suture, but due to a pushing back of the clypeal region, accompanied by the curving of the fronto-clypeal line, the anterior limit of the frons is difficult to determine. It is possible that in some cases the clypeal region has been so pushed caudad as to cut the postclypeus completely in two. Pharyngeal muscles are attached in this area, however, which is evidence of its clypeal nature. Weber (1930), in his very excellent book on the Hemiptera, gives figures of the longisections of the heads of an aradid and of the reduviid, Reduvius personatus, in which he shows the pharyn- geal muscles attached to the head capsule caudad of the anteclypeal area. He also recognizes the presence of the anteclypeus and postclypeus. We cannot recognize any external limits to the cephalic margin of the frons. The position of the antafossae (af) varies greatly within the sub- order. This fact has been extensively used as a character to divide the group. The divisions Cryptocerata and Gymnocerata were made on this basis, but, recently, doubt has been expressed as to the phylogenetic value of this character and these subgroups have been abandoned. Reft- erence to the figures will show that they may occur in almost any position. They may be covered by antennal shelves, hidden in pits, or placed on prominent tubercles. The most interesting fact is that with all this migra- tion of the antennae we find that the mandibular levers maintain their point of attachment at the base of the genal suture which somehow arrives at a point near the antafossae in all species. Hence they retain their value as landmarks as they did in the Homoptera. THe CLYPEAL ReGION.—Four areas can be recognized in this region in most forms, and they are homologous with the same areas in the Homoptera. They are the postclypeus, the anteclypeus, and the two para- clypeal areas. The caudal margin of the postclypeus cannot be determined exteriorly, as was discussed in the previous section. Its cephalic margin is seldom marked by a suture between it and the anteclypeus. Such a suture, how- ever, can be observed in A/yodochus serripes (Fig. 183) and in Neides PHYLOGENY OF HEMIPTERA—SPOONER 29 muticus (Fig. 185), although it does not appear in the nymphs of these forms (Figs. 181 and 184) and may be a secondary development. It occurs in both nymph and adult of Phymata sp. (Figs. 202 and 203). The postclypeus is a very limited area in some forms, and, as was pointed out above, it is perhaps entirely divided in some of the more specialized species. Usually without definite caudal or anterior boundaries it is a rather vague area in this suborder which has lead to the frequent state- ment that it is absent or that the clypeus consists of a single piece (Snodgrass (1935) and MacGillivray (1923)). Muir and Kershaw (1911) describe the early fusion of the frons with the clypeus in the embryo of the reduviid, Pristhescancus papuensis. No trace of a suture remains. However, these authors refer to the anteclypeus as the labrum and to the labrum as the epipharynx. This indicates that the clypeus consists of two parts in the embryo and that the postclypeus fuses with the trons. The anteclypeus, the tylus of systematists, is a well marked area in nearly all of the species of the Heteroptera. Its lateral margins are deeply invaginated along the so-called frontal sutures. The invagination from each side goes deeply into the head and meets the one from the opposite side and fuses with it. This forms a heavily sclerotized cylinder similar to that described for the homopteron Otiocerus wolfi (Fig. 346). The mandibular and maxillary stylets pass through this tube, and it also houses the salivary pump. It is found in nearly all of the Heter- optera (Figs. 347 and 348). The anteclypeus of Corixa sp. (Figs. 134 and 135) is of interest because of the widening of the distal margin and a turning up of the disto-lateral angles. This gives this sclerite a shape which is quite unique among the Hemiptera. A much less extensive broadening of the distal margin is seen in Cimex lectularius (Fig. 154) and in Lamprocanthia sp. (Fig. 155). Four families of the Heteroptera are without a definitely marked anteclypeus. These families are the Naucoridae, Pelocoris femoratus (Figs. 125, 126, 127, and 128), Notonectidae, Notonecta sp. (Figs. 130 and 131), Ochteridae, Ochterus americanus (Figs. 147 and 149), and the Nerthridae, Gelastocoris sp. (Figs. 148, 150, 298, and 299). Becker (1929) records the absence of a definite anteclypeus in Naucoris cimi- coides. There is no indication of any separation of the clypeal area into postclypeus and anteclypeus in these forms, and, furthermore, there are no anteclypeal invaginations supporting the hypopharynx. Heads that have been treated with caustic potash show the pharyngeal structures through the surface, and at first glance these appear to be the anteclypeus. The pharyngeal structures in these forms are developed entirely from the hypopharynx. They consist of the pharyngeal pump and two long wings, one extending from each corner of the hypopharynx dorsad into the head cavity, reaching the occipital border of the head. 30 ILLINOIS BIOLOGICAL MONOGRAPHS The paraclypeal areas are always well developed in the Heteroptera. They extend along each side of the anteclypeus and are bounded laterally by the genal suture. They have been termed the jugae by students of this suborder and have occasionally been referred to as the lorae. They are homologous with the paraclypeal areas of the Homoptera. Their extent varies greatly. They are smallest in Pelocoris femoratus (Fig. 220, pac) and in Notonecta sp. (Fig. 222). Their limits in these forms can be determined only by a study of the internal structure. Brochymena sp. (Figs. 208 and 209), Stethaulax marmoratus (Fig. 210), Corimelaena sp. (Fig. 211) and Cyrtomenus mirabilis (Fig. 212) show the greatest development of the paraclypeal areas. They are equal to or exceed the length of the anteclypeus and crowd the maxillary plates to the lateral or ventral aspect of the head. They are also comparatively long in Corythuca ciliata (Fig. 199) and Phymata sp. (Figs. 202 and 203). Intermediate lengths between these and Triphleps insidiosa (Fig. 158) may be observed in such forms as Nabis subcoleoptratus (Figs. 166 and 167), Corizus sp. (Figs. 188 and 189), and Neides muticus (Figs. 186 and 187). Tue Maxitrary PLates.—These structures in the Heteroptera are entirely homologous with those of the Homoptera. They are separated from the paraclypeal areas by the genal sutures and lie alongside of the anterior half of the anteclypeus in such forms as Belostoma flumineum (Figs. 116 and 117), Ranatra americana (Figs. 121 and 122), Hydro- metra martini (Fig. 145), Nabis subcoleoptratus (Fig. 166), and many other forms. Due to the elongation of the paraclypeal areas, the manil- lary plates are entirely lateral and ventral in Phymata sp. (Figs. 272 and 273), Brochymena sp. (Figs. 275 and 276), Corimelaena sp. (Fig. 278), Stethaulax marmoratus (Fig. 279), and Cyrtomoenus mirabilis (Fig. 280). The maxillary plates are fused with the gena and postgena without trace of sutures. They form most of the lateral and ventral aspects of the head. The maxillary and labial sutures described in the Homoptera (Muir, 1926) are not present in the Heteroptera. It is stated by Muir and Kershaw (1911b) that the basal joint of the labium frequently fuses with the maxillary plates and becomes a part of the head capsule. The author has found no morphological evidence of this in either nymphs or adults. Tue Buccurae.—The ventral margins of the maxillary plates are bent at an angle, in many species, forming a pair of projections which have been termed the bucculae (bw). They serve as a support to the labium when it is functioning and a protection to it when it is at rest. These structures are modifications of the maxillary plates in the opinion of most workers (MacGillivray, 1923b). Bugnion and Popoff (1911) state that Heymons considers them to represent the rudiments of the PHYLOGENY OF HEMIPTERA—SPOONER 31 maxillary palps. Many species of the Heteroptera lack these structures and they occur in varying degrees of development in the other species. They are lacking in Cimex lectularius (Figs. 235 and 237), Gelastocoris sp. (Figs. 234 and 236), and Systelloderus biceps (Figs. 248 and 249). Rudimentary bucculae may be seen in Triphleps insidiosus (Fig. 240) and Alydus sp. (Figs. 263 and 264). They are well developed in Lamprocanthia sp. (Fig. 238), Neides muticus (Fig. 261), Brochymena sp. (Fig. 277), and Stethaulax marmoratus (Fig. 279). Corythuca ciliata (Figs. 270 and 271) shows the most extensive development of the buc- culae. They are projected forward, in the adult, curve around the front of the labium and almost meet. An effort was made to use this character to show relationships be- tween the various families but no definite results were obtained. They are well developed in such obviously unrelated families as the Belostoma- tidae (Fig. 214), Saldidae (Fig. 238), Tingitidae (Fig. 271), and Penta- tomidae (Fig. 275). They are absent or rudimentary in many equally unrelated families. The bucculae are perhaps more universally well developed in the higher groups, especially in the Pentatomoidea. Tue Lasrum.—This sclerite is attached to the ventral or cephalic margin of the anteclypeus. The Heteroptera may be divided into three groups on the basis of the form of labrum. The first group consists of those forms having a broad, flap-like labrum, and the second contains those species with a long, narrow, triangular labrum. There are a num- ber of intergrading forms in these two groups, and they can be arranged in a fairly regular series. The labrum of the third group consists of a broad, flap-like sclerite with a long, pointed outgrowth from the epi- pharyngeal area which projects beyond the distal margin of the labrum. This projection has been termed the epipharynx (Fig. 145, ep7). The labrum of the first group has been described as the most primi- tive type found in the suborder Heteroptera and we find it characteristic of the following families: Cimicidae, Cimex lectularius (Figs. 152, 153, and 154), Saldidae, Lamprocanthia sp. (Figs. 155 and 156), Anthocor- idae, Triphleps insidiosus (Figs. 157 and 158), Naucoridae, Pelocoris femoratus (Figs. 126 and 127), Notonectidae, Notonecta sp. (Figs. 130 and 131), and Corixidae, Corixa sp. (Figs. 134 and 135). The families, Reduviidae, Sinea sp. (Fig. 159), Emesa brevipennis (Figs. 162 and 163) and Melanolestes abdominalis (Fig. 164); and Nabidae, Nabis subcoleoptratus (Fig. 167), show intermediate stages between the first and second groups. The labrum is rather broad but, nevertheless, longer than broad. Systelloderus biceps (Figs. 168 and 169), Ceratocombus vagans (Figs. 170 and 171), and Miris dolobratus (Fig. 173) possess labra that are narrow but comparatively short. The labrum reaches its greatest length in such forms as Belostoma flumineum 32 ILLINOIS BIOLOGICAL MONOGRAPHS (Fig. 118), Neides muticus (Figs. 184 and 185), Mvyodochus serripes (Fig. 183), Euryophthalmus succinctus (Fig. 179) and Harmoestes reflexulus (Fig. 266). The third group consisting of those species which possess an epi- pharyngeal projection, forms a very interesting and distinct unit. A study of Gerris marginatus (Fig. 226) and Naeogeus burmeisteri (Fig. 229) shows clearly that this projection extends from the under surface of the labrum and hence is purely epipharyngeal in character. It is not always so obvious that it arises from this region alone, as in Khagovelia obesa (Fig. 228), but careful observation proves it to be true in the most ob- scure cases. This epipharyngeal projection occurs in the following families: Gerridae, Gerris marginatus (Fig. 226); Veliidae, Rhagovelia obesa (Figs. 141, 142, 227, and 228) ; Mesoveliidae, M/esovelia bisignata (Figs. 143 and 230); Naeogeidae, Naeogeus burmeistert (Figs. 146 and 229); Ochteridae, Ochterus americanus (Fig. 149); and Nerthridae, Gelastocoris sp. (Fig. 148). The process is very small in the last two families. The question arises as to whether or not the greatly elongated labrum of the second group is a combination of the labrum and epipharynx of this third group. The ectal surface of the epipharynx might have become sclerotized and joined to the labrum without trace of a suture. That such an occurrence would be possible is suggested in Myodochus serripes (Fig. 183), Alydus sp. (Fig. 192), and Leptocoris trivittatus (Fig. 193). The base of the labrum in these forms is distinctly more sclerotized than the tip and a distinct line of differentiation 1s observed which has been rep- resented in the figures by dotted lines. This line does not indicate a suture. Is the basal portion labrum and the distal part the epipharynx? The writer prefers to leave the query unanswered until further evidence is at hand. There is no other indication of such an occurrence in other members of the group. The labrum furnishes us with evidence for one very distinct group of families in the Heteroptera and with a fairly good series showing pro- gressive development of the labrum which may prove of value in determining relationships among the remaining families. THe CAUDAL AND VENTRAL ASPECTS OF THE Heap.—The caudal or ventral margins of the maxillary plates are united with each other with- out trace of a suture, forming a continuous sclerotized plate (gw) ventrad or cephalad of the occipital foramen (of). This union of the maxillary plates with the accompanying sclerotization forms the outstanding differ- ence between the suborders Heteroptera and Homoptera. This area has been termed the gular area, although a true gula does not occur in this order. MacGillivray (1923) calls the region the genaponta but the author retains the older term for it. PHYLOGENY OF HEMIPTERA—SPOONER 38 The labium is attached to the cephalo-ventral margin of this plate which, in many species, is notched to receive it: Triphleps insidiosus (Fig. 309) and Ochterus americanus (Fig. 303). The labrum closes the cephalic side of this notch, as shown in Ranatra americana (Fig. 284), Pelocoris femoratus (Fig. 288), and Alydus sp. (Fig. 330). The labium is attached caudad of the cephalic margin in such forms as Brochymena sp. (Fig. 341) and Stethaulax marmoratus (Fig. 344). There is a large opening apparent in the head capsule in these forms when the labium is removed. This was described by MacGillivray (1923b) as an artifact which he termed the labiafossa (Figs. 340, 341, and 342, /f). A sclero- tized bridge extends across the cephalic margin of the labiafossa in some species, Brochymena sp. (Figs. 341 and 342, gy). This structure was termed the gymnoid by MacGillivray (1923b). Large projections extend into the head cavity from the margin sur- rounding the occipital foramen in many species. These structures are termed the occipitalia (oc) by MacGillivray (1923b). They are essen- tially apodemes and may be seen in Sinea sp. (Fig. 311), Melanolestes abdominalis (Fig. 315), Phymata sp. (Fig. 338), and Pelocoris femoratus (Fig. 287). They are extremely long, extending through the prothorax in Belostoma flumineum (Fig. 282), Ranatra americanus (Fig. 283), and Gerris marginatus (Fig. 293). The figures do not show the entire length of these structures. Two pairs of occipitalia are found in Pelocoris femoratus (Fig. 288). The function of these structures is to serve as places of attachment for muscles. The muscles which move the head are attached here as well as the protractor and retractor muscles of the maxillary stylets. The caudal or ventral aspects of the head in various Heteroptera are shown in the plates (Figs. 281-345). Comparatively few characters of importance in the study of relationships are found in this aspect. The complete lack of sutures renders it impossible to delimit the various areas of which it is composed. Tue TENTORIUM.—There is no trace of a tentorium in the Heterop- tera. MacGillivray (1923b) states that only the caudal two-thirds of the metatentoria are to be found in Benacus. The metatentorinae are wanting, and the remains of the metatentoria are, therefore, far removed from the usual point of invagination, and there is no evidence that any invagination has occurred. Ekblom (1926), Becker (1929), and Hamilton (1931) all describe a tentorium consisting of the body of the tentorium, the anterior arms, and the posterior arms. The structures which they have called the anterior and posterior arms of the tentorium are the hypo- pharyngeal evaginations similar to those described in the Homoptera. These evaginations project into the head capsule and form places for the attachment of the pharyngeal muscles and guides or supports for the 34 ILLINOIS BIOLOGICAL MONOGRAPHS maxillary stylets. The fusion of these posterior evaginations with the metatentoria was also described in the Homoptera. Hence, the two-thirds of the metatentoria described by MacGillivray are really these hypo- pharyngeal structures and the metatentoria are entirely wanting. The corpotentorium of the authors mentioned above is apparently the floor of the hypopharynx, as seen in the figures given by Becker (1929). The structures here described are all present in the Homoptera in addition to a rather typical tentorium. Therefore the structures in the Heteroptera must be homologous with the hypopharyngeal structures of the Homoptera and not with the tentorium. There is no evidence of any part of the tentorium in the Heteroptera. A peculiar structure is found in the Saldidae. A large, deep apode- mina is found along each epicranial arm of the nymph of Lamprocanthia sp. (Fig. 155, ap). These produce long, slender, heavily sclerotized apodemes in the adult which extend into the head cavity (Fig. 308). At first sight one is apt to homologize them with the pretentoria. They suggest the condition found in the Cicadellidae and described in the sec- tion on the tentorium of the Homoptera. They are not invaginated at the same point, however, in the two groups. Those in the Cicadellidae arise in the genal sutures, while in the Saldidae, they occur in the epicranial arms. They are not, therefore, homologous with the pretentoria but are secondary structures with no counterpart in other Heteroptera. Tue Lasium.—tThe labium of the Heteroptera was formerly con- sidered to vary in the number of segments it contained, having either three or four segments, and this fact was used in the classification of the group. Recent studies have led to the conclusion that all Heteroptera possess a four-segmented labium. All or part of the basal segment may become attached to the head capsule according to Muir and Kershaw (1911b). This conclusion was based upon embryological evidence, and further evidence must come from this source before we can hope to clarify the situation. We may still use the occurrence of three or four visible segments in the labium to help us in our classification, but we can no longer consider it to be of great phylogenetic importance. No morpho- logical evidence of this fusion was found. The writer did not include the labium in the present study. It shows some very interesting modifications and would repay extensive study. A few figures have been included in the plates to illustrate some of these variations (Figs. 392-398). The direction of the mouth opening as evidenced by the place of attachment of the labium is of some interest. Attempts have been made to use this character in the classification of the suborder. These attempts will be discussed later in this paper. The mouth opening is most nearly cephalad in such forms as Triphleps insidiosus (Figs. 239 and 240), PHYLOGENY OF HEMIPTERA—SPOONER 35 Melanolestes abdominalis (Fig. 245), and Systelloderus biceps (Figs. 248 and 249). The direction swings considerably ventrad in Emesa brevi- pennis (Figs. 243 and 244), Nabis subcoleoptratus (Figs. 246 and 247), and Sinea sp. (Figs. 241 and 242). It is definitely ventral in Neides muticus (Figs. 260 and 261), Alydus sp. (Figs. 263 and 264), and Piesma cinerea (Fig. 269). The opening occurs on the ventral surface caudad of the cephalic margin, as shown by the position of the labiafossa in Phymata sp. (Figs. 337 and 338), Brochymena sp. (Figs. 341 and 342), and Stethaulax marmoratus (Fig. 344). Tue MANprBuLar Levers.—The levers which attach the mandibular stylets to the head capsule and which increase the action of the extensor and retractor muscles of the stylets have been described in the Notonec- tidae by Geise (1883) and in Nepa and Naucoris by Heymons (1899). The author described them in the Aradidae (Spooner, 1920). It remained for Ekblom (1929) to make an extensive study of these levers and to make use of them in attempting to show the relationships between the families of the Heteroptera. He described four main types of these levers. The first type has a triangular lever attached to the membrane sur- rounding the base of the mandibular stylets. The second form is a three- branched. lever, one end of which is attached directly to the stylet. The third is a triangular form, attached directly to the stylet which is folded anteriorly, and has a double attachment to the head capsule. The fourth type consists of a quadrangular lever with double walls, closely attached to the base of the mandible but not firmly united with it. The protractor muscle is attached to the center of this type. He uses these four types of mandibular levers as the basis for dividing the Heteroptera into four groups. These groups will be discussed in a later section of this paper. The writer has studied the mandibular levers of all of the families of the Heteroptera in which material was available and has found them to be of considerable interest. Two of the types described by Ekblom were found to form rather clear-cut groups. These were his third and fourth types. The first and second groups were not easily separated in all cases, and evidence of at least two more types was found. Type one, the triangular lever attached to the membrane surrounding the base of the mandibular stylet, is found in by far the larger number of the Heteroptera. The large amount of variation within the group may be seen by comparing the figures (369-391). Several other species were examined and the levers were found to come within the range of varia- tion shown in the figures. A tendon of varying length attaches the lever to the membrane about the base of the stylet. The second type includes, according to Ekblom (1929), Ranatra (Fig. 356), Pelocoris (Fig. 358), and Notonecta (Fig. 359). Belostoma (Figs. 36 ILLINOIS BIOLOGICAL MONOGRAPHS 354 and 355) should also be included in this group. The great amount of variation is readily observed. A comparison with the lever of Melano- lestes (Fig. 357) shows that the most consistent difference from the first group les in the attachment to the mandibular stylets. It is attached directly to the base of the stylets in this second group, while in the first it is attached to the enclosing membrane. Levers of both nymph and adult of Belostoma (Figs. 354 and 355) were examined to determine the amount of difference between them. The same thing was done in the aradid, Aneurus sp. (Figs. 386 and 387). No essential change occurs between these stages of the insect. Pelocoris (Fig. 358) and Notonecta (Fig. 359) have levers which are sufficiently different to warrant further discussion. The lever of Pelo- coris is a long, slender loop with one end attached to the head capsule and the other end to the mandibular stylet. The protractor muscle is fast- ened to the elbow of the loop and a contraction of the muscle brings the ends of the loop toward each other and thus forces the stylet forward. This arrangement is entirely different from that found in any other species. Two pieces make up the lever of Notonecta (Fig. 359), a larger triangular piece attached to the head capsule, and a smaller piece at- tached at an angle just before the apex of the first. The condition of the specimens at hand made it impossible to determine just where the muscles are attached. This is another unique form of lever. The second of Ek- blom’s groups, then, appears to contain at least three types of levers. The third group described by Ekblom is found only in the Corixidae, Coriva sp. (Fig. 349). This form is triangular and is folded at the outer margin with a rod-like extension extending to the mandible and uniting directly with it. The fourth type, as was stated, forms a fairly well isolated group. The quadrangular shape of the lever with the rod-like projection fastening to one face and extending directly to the mandibular stylet is found in Gerris marginatus (Fig. 360), Rhagovelia obesa (Fig. 361), Mesovelia bisignata (Fig. 362), Hydrometra martini (Fig. 363), and Naeogeus bur- meistert (Fig. 364). Ochterus viridifrons (Fig. 365) shows a modifica- tion of this type in that the rod-like extension is attached to the edge of the plate and that the plate approximates a triangle in form. The lever ‘s attached directly to the mandibular stylet. Ochterus americanus (Fig. 366) has the mandibular lever still more triangular in outline, with the arm very slender and tendon-like, while in Gelastocoris sp. (Fig. 368) the lever is in the form of a perfect triangle with one corner attached directly to the mandibular stylet. It is worth calling attention here to the fact that, if we include Och- terus and Gelastocoris, this group includes all of those forms which possess the epipharyngeal process described in the section on the labrum, PHYLOGENY OF HEMIPTERA—SPOONER 37 Further discussion of these relationships revealed by the study of the mandibular levers will be made in the section on phylogeny. A number of species and varieties of Euschistus were examined to determine the extent of variation within the genus. Ochterus viridifrons (Fig. 365) and Ochterus americanus (Fig. 366) show a considerable dif- ference in the shape of the lever. Three species and two varieties of Euschistus were examined, but they showed only minor variations in the form of these structures (Figs. 390 and 391). With the turning in of the direction of the mouth opening from ceph- alad to ventrad there occurs a bending of the mandibular stylets (Figs. 367, 369, 371, 375, and 376). The levers and the mandibular bases work in the same plane as in those with a cephalic mouth opening, the bend in the stylets accommodating the change in the direction of the mouth opening. Tue Maxittary Stytets.—The maxillary stylets are not attached to the head capsule by means of levers in any heteropteron examined by the writer. Their point of attachment varies so greatly that they cannot serve as landmarks for the head sclerites, and a serious study of them has not been included in this work. It was observed that in the Gerridae, Gerris remigus, the maxillae followed the occipitalia back into the mes- othorax. Muscles were attached to the occipitalia and to the body wall of the mesothorax. PHYLOGENY OF THE HETEROPTERA The Heteroptera is a much larger and more varied group than the Homoptera and consequently the relationships within this group are much more difficult to determine. The present studies have brought to light some characters which are unquestionably of value in deciphering these relationships, and while much remains to be done they are given here in the form of suggestions which may lead to further discoveries. This suborder appears to be an offshoot of the early Homoptera. Evi- dence for this statement is, first, the earlier appearance of the Homoptera as fossils and, second, the similarity of the anteclypeal region of some of the Fulgoridae (Otiocerus wolfii, Fig. 346) with that of many heterop- terons (Belostoma flumineum, Fig. 347 and Euschistus tristigmus, Fig. 348). The peculiar modification of the alimentary canal known as the filter chamber, in which the caudal part of the intestine loops forward and becomes imbedded in the walls of the ventriculus, is found in most Homoptera. The fact that it is absent in the Fulgoridae and in all of the Heteroptera (Kershaw, 1913) is further indication of the probable ancestral relationship between these two groups. Reuter (1910) has given a detailed account of the historical develop- 38 ILLINOIS BIOLOGICAL MONOGRAPHS ment of the classification of the Heteroptera to that date and Ekblom (1929) has brought it up to the present time. A detailed account is not necessary here and only a few of the major contributions will be discussed. Reuter (1884-1891) used the classification of Fieber (1851) in which the Heteroptera was divided into two major groups based on the position of the antennae. These two groups were known as the Cryptocerata and the Gymnocerata. Kirkaldy (1908) discarded these two divisions and proposed two groups based on the method of articulation of the meta- coxae which he named the Pagiopoda and the Trachalopoda. He regarded the Pentatomidae as containing those forms, which have retained most of the primitive characters of the Heteroptera, and hence reversed the usually accepted arrangement of the families. The grouping into the Cryptocerata and the Gymnocerata was aban- doned by Reuter (1910) who divided the Heteroptera into six series: Hydrobiotica, Trichotelocera, Anonycha, Onychiophala, Polyneura, and Peltocephala. He based these groups primarily upon the following char- acters: the presence or absence of ocelli and aroli, the form and structure of the egg, and the condition of the sternal sclerites. His scheme of classification has been largely used since and still forms the basis for most of the present-day work. Considerable doubt has been expressed recently upon the dependability of the above characters for the separation of the groups. McAtee and Malloch (1924, 1925a, and 1926) point out the modification of the sternal sutures which accompanies the degree of development of the wings. Ekblom (1929) rejects the shape of the egg as a phylogenetic character, and Myers (1924) and Holloway (1935) show that our incomplete knowledge of tarsal structures renders any classification based upon them uncertain. Ekblom (1929) has given us the most recent scheme of classification of this suborder and his work is by far the most important contribution to the subject in recent times. He bases his classification upon the early scheme of Dufour (1833) and supplies new characters to confirm Dufour’s ideas. Dufour divided the Heteroptera into three series, the Geocorises, the Hydrocorises, and the Amphibicorises. Borner (1904) added the Sandaliorrhyncha to include the family Corixidae. These four series are recognized by Ekblom and justified primarily by the types of mandibular levers described in a previous section of this paper. Evidence obtained in the present study lends support to the validity of this grouping with some minor changes perhaps suggested. The San- daliorrhyncha, containing the single family Corixidae, is quite evidently valid. The corixids are a very isolated and highly specialized group. The form of the anteclypeus suggests a possible relationship between them and the Saldidae or Cimicidae, but this relationship is extremely remote. PHYLOGENY OF HEMIPTERA—SPOONER 39 The Hydrocorisae is the least unified group of the four. It contains the families Nepidae, Belostomatidae, Naucoridae, and Notonectidae. As has been pointed out in a previous section of this paper, there are three distinct types of levers in this group, and perhaps the group should be split into three. The Nepidae (Fig. 356) and the Belostomatidae (Fig. 355) would form one group having the three-branched lever described by Ekblom (1929) as typical of the Hydrocorisae. The Naucoridae ( Fig. 358) form a group characterized by having the lever in the form of a long, slender loop ; while the Notonectidae (Fig. 359) would represent the third group, with a lever consisting of two distinct pieces. The last two families agree in lacking any evidence of the anteclypeus (Figs. 127 and 131). The third series, the Amphibicorisae, forms a very well defined group. It contains the families Ochteridae, Nerthridae, Naeogeidae, Hydro- metridae, Mesoveliidae, Veliidae, and Gerridae. These forms all possess the epipharyngeal projection from the labrum (Figs. 221 and 226-231), and the mandibular levers (Figs. 360-366) agree in being attached directly to the mandibular stylets. Most of the levers are quadrangular in form, with the Ochteridae showing a gradual shift to the triangular type char- acteristic of the Geocorisae (Figs. 365 and 366). The Ochteridae and the Nerthridae, on the other hand, agree with the Naucoridae and the Notonectidae in lacking any evidence of the anteclypeus, and thereby bridge the gap between the Amphibicorisae and the Hydrocorisae. The remaining families of the Heteroptera are included in the series Geocorisae. This forms a very large group, all of the members of which possess a more or less triangular mandibular lever attached to the mem- brane surrounding the base of the stylet rather than directly to the stylet. The dead structures give very little aid in subdividing this group or in suggesting relationships between the families. The danger of misinterpreting modifications accompanying similarity of habits is encountered in a group so large as this. A very interesting case of this has been described by China (1931). He states that the coiling of the stylets characteristic of the Aradidae (Figs. 386 and 387) is also found in the European family Termitaphididae and that they are partially coiled in the Plataspidae, another old world family. Bozius also has a similar structure. These four otherwise unrelated groups with similar long coiled stylets all have the habit of feeding on fungus. The predacious forms in the North American families seem to agree in certain characteristics, such as the comparatively wide labrum, the cephalic direction of the mouth opening and in the lack of bucculae. There are, however, many exceptions to these generalities and this may also be a case of morphological parallelism. The families Cimicidae (Fig. 152), Anthocoridae (Fig. 157), and Saldidae (Fig. 156) form a group characterized by a very wide, flap-like 40 ILLINOIS BIOLOGICAL MONOGRAPHS labrum. The bucculae, on the other hand, are well developed in the Saldidae, rudimentary in the Anthocoridae, and wanting in the Cimicidae. The Reduviidae (Figs. 161, 163, and 165), the Nabidae (Fig. 167), and the Enicocephalidae ( Fig. 168) show intermediate stages in regard to the width of the labrum, The Cryptostemmatidae (Fig. 170) and the Miridae (Fig. 173) seem to be related followed, perhaps, by the Lygaeidae (Fig. 176), Pyrrhocoridae (Fig. 180), Corizidae (Fig. 189), and Alydidae (Fig. 192). The last three families show progressive stages in the elonga- tion of the paraclypeal areas and the accompanying lateral or ventral posi- tion of the maxillary plates. This is characteristic of the Pentatomoidea, including the families Pentatomidae (Fig. 208), Cydnidae (Fig. 212), and the Corimelaenidae (Fig. 211). The Aradidae (Fig. 207), the Phymatidae (Fig. 203), the Piesmidae (Fig. 196), and the Tingitidae (Fig. 109) seem to stand rather alone with the great development of the bucculae in common. The Piesmidae (Fig. 196) shows an enormous elongation of the paraclypeal areas. The Neididae (Fig. 185) also possess well developed bucculae but otherwise agree with the Lygaeidae (Fig. 176). The head structures, on the whole, give comparatively little help in subdividing the Geocorisae. Studies of other structures will be necessary to determine the actual relationships in this group. Some such studies have been made and a brief review of them will be of value. Taylor (1918) studied the thoracic sclerites and divided the Heterop- tera into five groups on the basis of thoracic and coxal characters. Four of these groups he states as being similar in general characteristics. Notonectidae, Corixidae, Belostomatidae, and Nepidae form the first and most distinctive group, all with large metathoracic coxae overlapped by the epipleura and having the meso- and metathoracic pleurae distorted. This group corresponds somewhat with the Sandaliorrhyncha and the Hydrocorisae. The second group includes the Miridae, Nabidae, and Cimicidae which have exposed meso- and metathoracic coxae. The Redu- vudae and the Phymatidae form the third group, characterized by the presence of a true coxal cleft in the metathorax. The fourth group, with the mesothoracic scutellum prolonged over the abdomen, includes the Coreidae, Lygaeidae, Tingitidae, Pentatomidae, Scutellaeridae, and Cori- melaenidae. The Neididae, Gerridae, and Emesidae form the fifth group, all having the mesothoracic pleurae lengthened horizontally. The last four groups do not agree with the findings in the study of the head structures. Tullgren (1918) made a very interesting study of the occurrence of Trichobothria in the Heteroptera. These are described by the author as auditory hairs and are apparently the tactile sense organs described by Snodgrass (1935). They have been extensively used in the classification of the spiders. Tullgren found them present in eight families. The PHYLOGENY OF HEMIPTERA—SPOONER 41 Thyreocoridae, Scutellaeridae, and Pentatomidae had them arranged in the same pattern on the same sternites. The Coreidae, Neididae, and Piesmidae each possessed them and each family had a characteristic arrangement of them. The Pyrrhocoridae and the Lygaeidae agreed in having them arranged in the same pattern but differing from those men- tioned above. He found no evidence of these structures in the other families of the Heteroptera nor in the Homoptera. The genitalia in the Hemiptera were studied by Pruthi (1925). He recognized two main types of genitalia in the Heteroptera which he designated as the pentatomid type and the reduviid type. The pentatomid type included the families Saldidae, Aradidae, Pentatomidae, Coreidae, Neididae, and Lygaeidae. All of the remaining families were included in the group having the reduviid type of genitalia. The metasternal scent glands were studied by Brindley (1930). He found them present in most of the families. They were absent in the Nepidae and the Hydrometridae. Unfortunately he apparently did not investigate the Naeogeidae, Ochteridae, Nerthridae, Anthocoridae, Veliidae, or Mesoveliidae. China (1933) bases his classification partially on habits and points out a series originating in the rapidly running and flying, littoral Saldidae and Ochteridae through the more sluggish Nerthridae to the typical aquatic forms Nepidae and Belostomatidae. He points out the structural char- acters accompanying these changes in habit. He does not give detailed reasons for the remainder of his classification. This brief review of the important works on the comparative morphology of the Heteroptera indicates that further studies are badly needed, particularly detailed comparative studies of the various parts of the body. Until these are made we cannot hope to arrange the Geocorisae in any satisfactory phylogenetic series. The accompanying diagram (Text-figure 2) gives a graphic idea of the relationships of the Heteroptera suggested by the study of the head capsule. SUMMARY A comparative study of the head capsule of the adults and nymphs of all of the North American families of the Hemiptera in which material was available has been made. This included all of the families of the suborder Homoptera excepting the Coccidae and all of the Heteroptera excepting the families Thaumasticoridae, Microphysidae, and Terma- tophylidae. Nymphs were available in all of the families studied except the Piesmidae and the Hydrometridae. Evidence has been advanced to show that the Homoptera represent ILLINOIS BIOLOGICAL MONOGRAPHS 42 aDsSy40I/9 1Y duly @DSSAOI osphy DY wut Yo opube 2D PIP DAY 9 aDD//AN D2 Y a0 p/a/Us/ 9 aDpss49d0Yf{Uy abp/p/D> aDpsuaD/saw/so 4 aoplupAay aD psluofdDjV3/ aDPlMsaly abp ae aD PIPAV anp/ 2470S ODD IbUL] A aD pijodih) p> 4 aD9 4109094) ae DDIM LIAN aDp/4efyrO S appsaboanyy—_ aDp/tt aworpA, mg a Dpl//@A0S3lWW— & aDpli/aQ app/44aQ—_®& anp/4omnDoy—_© avpls2aU0fON—_ NX aopiday~ _& aDpy, pwopsojag— + Ly ODPIX/40 7 v 3 8 uU K XN es © eS ae Xs <8 S ae & 2 > S 1°) << s a Text-Ficure 2 PHYLOGENY OF HEMIPTERA—SPOONER 43 the more primitive suborder and that some members of the Fulgoridae have retained some of the most primitive characteristics found in the group. A series of forms was described showing the gradual develop- ment of the paraclypeal areas from the postclypeus by the extension of the so-called frontal sutures. The homologies of these areas have given rise to more discussion than any other part of the hemipterous head. The structure of the head, particularly of the tentorium, suggests that the other families of the Homoptera have developed from the primitive Cercopidae. The two subfamilies of the Cercopidae differ considerably in head structure. The Cercopinae, characterized by a greatly reduced frons gives rise to the Tettigonidae, Membracidae, Cicadidae, Psyllidae, and Aphididae; while the Aphrophorinae, members of which have retained the large frons characteristic of the Fulgoridae, leads to the Cicadellidae, Aleyrodidae, and Coccidae. The Tettigonidae has alternately been con- sidered as a subfamily of the Cicadellidae and as a separate family. This study indicates that it is a distinct family considerably removed from the Cicadellidae. Facts are presented to show that the parts of the heteropterous head are homologous with those of the Homoptera, a fact which has often been denied. This removes the objection formerly advanced, against deriving the Heteroptera from the Homoptera. The Heteroptera were found to lack any trace of a true tentorium. The structures usually described as such originate from the hypopharynx. These hypopharyngeal structures are also found in the Homoptera in addition to a nearly typical tentorium. The Heteroptera are best grouped into the four series Sandaliorr- hyncha, Hydrocorisae, Amphibicorisae, and Geocorisae. The Antho- coridae or Cimicidae are probably the most primitive forms of the Heteroptera and belong to the Geocorisae. The form of the labrum, the type of mandibular lever, the direction of the mouth opening and the development of the bucculae are the most important structures of the head as far as showing the relationships between the families is concerned. The Sandaliorrhyncha is a small and unique series, rather completely isolated from the rest of the Heteroptera. The second series, the Hydro- corisae, is not clearly limited. Three types of mandibular levers are found in these forms which perhaps justifies their separation into three groups. The Amphibicorisae forms a very well defined group character- ized by a single type of mandibular lever and also by the development of an epipharyngeal appendage from the labrum. The mandibular lever in the family Ochteridae, of this group, shows a modification in shape toward that found in the most primitive of the Geocorisae, which perhaps indi- cates the origin of the Amphibicorisae from that group. Four families, two in the Hydrocorisae, Notonectidae, and Naucoridae, He ILLINOIS BIOLOGICAL MONOGRAPHS and two from the Amphibicorisae, Ochteridae, and Nerthridae, agree in lacking all evidence, both external and internal, of an anteclypeal area. This may bridge the gap between these two series. The Geocorisae is a large and complex series, the relationships ot which remain rather obscure. Detailed comparative studies of other body parts are needed to enable us to understand this group. The form of the labrum presents a series of the Cimicidae, Anthocoridae, Saldidae, Reduviidae, Nabidae, Enicocephalidae, and Miridae, in the order named. The Cryptostemmatidae, Miridae, Lygaeidae, Pyrrhocoridae, and Neididae seem to show intermediate stages in several of the head char- acters. The Aradidae, Phymatidae, and Tingitidae stand more or less isolated, while the Corizidae, Alydidae, Coreidae, Piesmidae, Pentatom- idae, Cydnidae, and Corimelaenidae show progressive enlargement of the paraclypeal areas and an accompanying ventral position of the maxillary plates. PHYLOGENY OF HEMIPTERA—SPOONER 45 BIBLIOGRAPHY AmatI, P. R. 1914. The Mechanism of Suction in the Potato Capsid Bug, Lygus pabulinus Linn. Proc. Zool. Soc. Lond., pp. 685-733. Amyot, C. J. B., and Servite, A. 1843. Hemipteres. Paris. Becker, E. 1929. Zum Bau des Kopfes der Rhynchoten. I. Teil: Bau des Kopfes von Naucoris cimicoides. Rev. Zool. Russe, 9:54-96. BercrotuH, E. 1924. On the Isometopidae of North America. Notulae Ent., 4:3-9. BeresI, A. 1909. Gli Insett1. BLATCHLEY, W. S. 1926. Heteroptera of Eastern North America. Nature Publishing Co., Indianapolis, Ind. Borne_er, C. 1904. Zur Systematik der Hexapoden. Zool. Anz., 27:511-533. 1929. Mandibeln und Maxillen bei Psociden, Thysanoptera, und Rhynchoten. Zeits. fur wissen. Insektenbiol. Berlin, n. s., 24:108-116. Brancu, H. 1914. Morphology and Biology of the Membracidae of Kansas. Kans. Univ. Science Bull., n. s., 8:75:115 (1913). Britton, W. E. 1923. The Hemiptera of Connecticut. Bull. Conn. State Geol. and Nat. Hist. Surv., 34:1-807. Bucnion, E., and Poporr, N. 1911. Les Piéces Buccales de Hemipteres. Arch. Zool., Paris, Sér. 5, 7:643-674. Curna, W. E. 1924. A New Genus of Peloridiidae from Tasmania. Ent. Mo. Mag., 60: 199-203. 1927. A Sub-brachypterous Male of Peloridtium hammontorum Breddin. Ann. and Mag. Nat. Hist., (9) 19:622-625. 1931. Morphological Parallelism in the Structure of the Labium in the Hemipterous Genera Coptosomoides and Bozius in Connection with the Mycetophagus Habit. Ann. and Mag. Nat. Hist., (10) 7:281-286. 1933. A New Family of Hemiptera-Heteroptera with Notes on the Phylogeny of the Suborder. Ann. and Mag. Nat. Hist., (10) 12:180-196. Curna, W. E., and Myers, J. G. 1929. Revision of the Miridae and Related Families. Ann. and Mag. Nat. Hist., (10) 3:97-125. Comstock, J. H. 1915. Manual for the Study of Insects. Comstock Publishing Co., Ithaca, N. Y. 1925. An Introduction to Entomology. Comstock Publishing Co., Ithaca, N. Y. Comstock, J. H., and Kocut, C. 1902. The Skeleton of the Head of Insects. Amer. Nat., 36:13-45. Crampton, G. C. 1921. The Sclerites of the Head and the Mouthparts of Certain Immature Insects. Ann. Ent. Soc. Amer., 14:65-110. 46 ILLINOIS BIOLOGICAL MONOGRAPHS 1922. Evidences of Relationships Indicated by the Venation of the Forewings of Certain Insects with Special Reference to the Heteroptera. Psyche, 29:33-41. 1927. Eugereon and the Ancestry of the Hemiptera, Psocids and Hymenoptera. Bull. Brooklyn Ent. Soc., 22:1-13. 1928. The Eulabium, Mentum, Submentum, and Gular Region of the Insects. Jour. Ent. and Zool., 20:1-15. 1932. A Phylogenetic Study of the Head Capsule in Certain Orthopteroid, Psocid, Hemipteroid, and Holometabolous Insects. Bull. Brooklyn Ent. Soc., 27:19-49. Crawrorp, D. L. 1914. The Jumping Plant-lice of the New World. Bull. U. S. Nat. Mus., pp. 1-182. Davipson, J. 1913. The Structure and Biology of Schizoneura lanigera Hausman. Quart. Jour. Micro. Sci., 28:653-701. 1914. On the Mouthparts and Mechanism of Suction in Schizoneura lanigera. Jour. Linn. Soc., 32:307-330. DESHPARDE, V. G. 1933. On the Anatomy of Some British Aleurodidae. Trans. Ent. Soc. Long., 81:117-232. Durour, L. 1833. Recherches Anatomique et Physiologiques sur les Hemipteres. Acad. de Sci. Paris, 4: 129-462. DumertL, A. M. C. 1806. Zoologie Analytique au Méthode Naturelle de Classification des Ani- maux. Paris. Exeiom, T. 1926. Morphological and Biological Studies of Hemiptera-Heteroptera. Part I. Zool. Bidrag fran Uppsala, 10:31-180. 1929. New Contributions to the Systematic Classification of Heteroptera. Ent. Tidsk., 50:169-180. 1931. Morphological and Biological Studies of the Swedish Families of Hemiptera-Heteroptera. Zool. Bidrag fran Uppsala, 12:113-150. Esakt, T., and Cura, W. E. 1928. A Monograph of the Helotrephidae, Subfamily Helotrephinae. Eos, 4:129-172. Ferris, G, F. 1934. Setae. Can. Ent., 66:145-150. Ferris, G. F., and CHAMBERLIN, J. C. 1928. On the Use of the Word “Chitinized.” Ent. News, 39:212-215. FIezeEr, F. X. 1851. Genera Hydrocoridum Secundum Ordinen Naturalen in Familias Dis- posita Pragae. GeIsE, O. 1883. Mundtheile der Rhynchoten. Arch. f. Naturg., 49:315-374. Grove, A. J. 1919. Anatomy of the Head and Mouthparts of Psylla mali with Some Remarks on the Function of the Labium. Parasitology, 11:456-488. PHYLOGENY OF HEMIPTERA—SPOONER 47 Hamitton, M. A. 1931. The Morphology of the Water Scorpion, Nepa. Proc. Zool. Soc. Lond., pp. 1067-1136. HanopiirscH, A. 1908. Die Fossilen Insecten und die Phylogenie der Rezenten Formen. Leipzig. HARGREAVES, E. 1915. Mouthparts of Aleyrodidae. Ann. App. Biol., 1:303-334. Hewer, K. 1889. Die Embryonalentwicklung von Hydrophilus piceus L. Jena. Herriot, A. D. 1934. The Renewal and Replacement of the Styles of Sucking Insects During Each Stadium and the Method of Penetration. Can. Jour. Res., 11:602-612. Heymons, R. 1896. Die Mundtheile der Rynchota. Ent. Nachr. Jahrg. 22, p. 173. Vorlauf. Mitteil. 1899. Beitrage zur Morphologie und Entwicklungsgeschichte der Rhynchoten. Abhandl. der Kais. Leopold. Carol. Deutsch Akad. der Natur., 74:355-456. Hotway, R. T. 1935. Preliminary Note on the Structure of the Pretarsus and Its Possible Phylogenetic Significance. Psyche, 42:1-24. Horvat, G. 1915. Monographie des Mesoveliides. Ann. Mus. Nat. Hungarici, Budapest. Ke toc, V. L. 1905. American Insects. New York. KersHaw, J. G. C. 1910. A Memoir on the Anatomy and Life History of the Homopterous Insect, Pyrops candelaria. Zool. Jahrb. Abt. fiir Syst. Geo. und Biol., 29:105-125. 1913. Anatomical Notes on a Membracid. Ann. Soc. Ent. Belgique, 57:191-201. Kersuaw, J. G. C., and Murr, F. 1922. The Genitalia of the Auchenorhynchus Homoptera. Ann. Ent. Soc. Amer,, 15:201-212. KirKALpy, G. W. 1906a. Biological Notes on the Hemiptera of the Hawaiian Isles. Proc. Haw. Ent. Soc., 1:135-161. 1906b. List of the Genera of Pagiopodus Hemiptera-Heteroptera with Their Type Species, from 1758-1904. Trans. Amer. Ent. Soc., 32:117-156. 1908. Some Remarks on the Phylogeny of the Hemiptera-Heteroptera. Can. Ent., 40:357-364. Leon, N. 1888. Beitrage zur Kenntnis der Mundteile der Rhynchoten. Jena. 1901. Recherches Morphologique sur les Piéces Labials des Hydrochora. Bull. Soc. des Méd. et Natur. et Jassy, pp. 1-13. MacGiriivray, A. D. 1923a. The Value of Landmarks in Insect Morphology. Ann. Ent. Soc. Amer., 16:77-84. 1923b. The External Insect Anatomy. Scarab Co., Urbana, Ill., pp. 1-368. 48 ILLINOIS BIOLOGICAL MONOGRAPHS Martatrt, C. L. 1895. The Hemipterous Mouth. Proc. Ent. Soc. Wash., 3:241-249. Mayer, P. 1874-75. Anatomie von Pyrrhocoris aptera. Archiv. fur Anat. und Phys., 1874, pp. 313-347, 1875, pp. 309-355. McArtee, W. L., and Mattocu, J. R. 1924. Some Annectant Bugs of the Superfamily Cimicoideae. Bull. Brooklyn Ent. Soc., 19:69-82. 1925a. Another Annectant Genus (Hemiptera, Cimicoideae). Proc. Biol. Soc. Wash., 38:145-148. 1925b. Revision of the Bugs of the Family Cryptostemmatidae. Proc. U. S. Nat. Mus., 67: Art. 1, 153 pp. 1926. Further on Annectant Bugs. Bull. Brooklyn Ent. Soc., 21:43-47. MEEK, W. J. 1903. On the Mouthparts of Hemiptera. Bul. Univ. Kans., 2:257-277. Mericuar, L. 1905. Beitrag zur Kenntnis der Homopterenfauna Deutsch Ost-Afrikas. Wien Ent. Zeit. 24:279-304. Murr, F. 1923. On the Classification of the Fulgoroidea. Proc. Hawaiian Ent. Soc., 5:205-247. 1926. Notes on the Head of the Cicada. Ann. Ent. Soc. Amer., 19:67-73. 1929. The Tentorium of the Hemiptera Considered from the Point of View of the Recent Work of Snodgrass. Ent. Mo. Mag., 65:86-88. 1931. A Criticism of Dr. Hansen’s Theory of the Maxillulae in Hemiptera. Ent. Mo. Mag., 67:51-53. Murr, F., and Kersuaw, J. G. C. 191la. On the Homologies and Mechanism of the Mouthparts of Hemiptera. Psyche, 18:1-12. 1911b. Embryological Stages of the Head of Pristhesancus papuensis. (Reduviidae). Psyche, 18:75-79. 1912. Development of the Mouthparts of the Homoptera with Observations on the Embryo of Siphanta. Psyche, 19:77-89. Murtt, B. K. 1929. The Suctorial Apparatus of Cicada. Mysore Univ. Jour., 3:12-55. Myers, J. G. 1924. Further on the Termitaphididae. Psyche, 31:239-278. 1928. The Morphology of the Cicada. Proc. Zool. Soc. Lond., pp. 365-472. Myers, J. G., and Cuina, W. E. 1929. Systematic Position of the Peloridiidae as Elucidated by a Further Study of the External Anatomy of Hemidoecus leai China. Ann. and Mag. of Nat. Hist., (10) 3:282-294, NEISWANDER, C. R. 1925. On the Anatomy of the Head and Thorax in Ranatra. Trans. Amer. Ent. Soc., 51:311-320. NELson, J. A. 1915. The Embryology of the Honey Bee. Princeton Univ. Press. OEsTLUND, O. W. 1918. Contribution to a Knowledge of the Tribes and Higher Groups of the Family Aphididae. 17th Rept. Minnesota State Ent., pp. 46-72. PHYLOGENY OF HEMIPTERA—SPOONER 49 Oszorn, H. 1898. The Phylogeny of the Hemiptera. Proc. Ent. Soc. Wash., 3:185-190. OsHANIN, B. 1912. Katalog der Palarktischen Hemipteren. Berlin. Prurut, H. S. 1925. Morphology of the Male Genitalia in Rhynchota. Trans. Ent. Soc. Lond., pp. 127-254. Reuter, O. M. 1884-91. Hemiptera Gymnocerata Europe. Acta Soc. Scient. Fennicae, Vols. 13 and 14. 1910. Neue Beitrage zur Phylogenie und Systematik der Miriden. Acta Soc. Scient. Fenn., 37:1-172. 1911-12. Bemerkungen uber mein neues Heteropterensystem. Ofversigt of Finska Vetehskaps Societ. Forh., 54:1-62. Ritey, W. A. 1904. The Embryological Development of the Skeleton of the Head of Blata. Amer. Nat., 38:777-810. Scuiopte, J. C. 1869. Nogle nye Honedsaetinger af Rhynchternes Morphologi og Systemat. Natur. Tidsk. (3) 7:237-266. Smiru, J. B. 1892. Notes on the Homology of the Hemipterous Mouth. Proc. Amer. Assoc. Adv. Sci., 40:325. 1898. Essay on the Development of the Mouthparts of Certain Insects. Trans. Philos. Soc., 19:175-198. Snoperass, R. E. 1921. The Mouthparts of the Cicada. Proc. Ent. Soc. Wash., 23:1-15. 1927. The Head and Mouthparts of the Cicada. Proc. Ent. Soc. Wash., 29:1. 1928. Morphology and Evolution of the Insect Head and Its Appendages. Smiths. Misc. Coll., 81:3:1-158. 1935. Principles of Insect Morphology. McGraw Hill Book Co., New York. Spooner, C. S. 1920. A Note on the Mouthparts of the Aradidae. Ann. Ent. Soc. Amer., 13:121-122. Stickney, F. S. 1934. The External Anatomy of the Parlatorian Date Scale, Parlatoria balnchardi, with Studies of the Head Skeleton and Associated Parts. U.S. Dept. Agr. Tech. Bull. 421, pp. 1-67. Taytor, L. H. 1918. Thoracic Sclerites of Hemiptera. Ann. Ent. Soc. Amer., 11:225-249, Trttyarp, R. J. 1918. Note on the Origin of Heteroptera. Proc. Linn. Soc. New So. Wales, 42:586-592. 1921. The Genus Mesogereon. Proc. Linn. Soc. New So. Wales, 46:270-284. 1926. The Fossil Record of Insects. The Insects of Australia and New Zea- land, pp. 468-483. Tower, D. G. 1913. External Anatomy of the Squash Bug. Ann. Ent. Soc. Amer., 6:427-437. TULLGREN, A. 1918. Zur Morphologie und Systematik der Hemiptera I. Ent. Tidsk., 39: 113-133. 50 ILLINOIS BIOLOGICAL MONOGRAPHS Unter, P. R. 1875. Report upon the Collections of Hemiptera Made in Portions of Nevada, Utah, and California. Col. U. M. and Ariz. during the years 1871-73-74. Bul. U. S. Geol. and Geog. Surv., 1:1827. VanDuzee, E. P. 1917. Catalog of the Hemiptera of North America. Univ. Calif. Tech. Bull, 2:1-902. Vickery, R. A. 1908. A Comparative Study of the External Anatomy of Plant Lice. 12th Rept. Minnesota State Ent., pp. 178-191. Wacker, E. M. 1931. On the Clypeus and Labium of Primitive Insects. Can. Ent., 65:75-81. Weser, H. 1929. Kopf und Thorax von Psylla mali. Zeits. fur Morph. und Okologie der Tiere, 14:59-156. 1930. Biologie der Hemipteren. Berlin, pp. 1-543. WHEELER, W. M. 1889. The Embryology of Blatta and Doryphora. Jour. Morph., 3:291-374. PHYLOGENY OF HEMIPTERA—SPOONER 51 ABBREVIATIONS USED IN THE PLATES anteclypeus antafossa antenna apodeme antennal shelf or tubercle attachment of mandibular lever to head capsule buccula clypeus corpotentorium epicranial arm epipharynx epicranial stem frons gena gula or gular area gymnoid mandibular lever labium labrum lf m mp ms mt oc labiafossa mandible maxillary plate maxillary suture metatentorium ocellus occipital parademe of occipitalia occipital foramen paraclypeus postcly peus postgena pharyngeal pump muscles protractor muscles of mandible pretentorium retractor muscles supratentorium vertex ILLINOIS BIOLOGICAL MONOGRAPHS PLATE I Cephalo-ventral aspect of the head Fic. 1—Otiocerus degeerii, adult. Fic. 2—Lamenia sp., adult. Fic. 3—Amaloptera uhleri, adult. Fic. 4.—Cyarda melichari, adult. Fic. 5.—Acanalonia sp., nymph. Fic. 6.—Ormenis pruinosa, adult. Fic. 7.—Pelitropis rotatula, adult. Fic. 8—Olharus vicarius, adult. Fic. 9.—Catonia impunctata, adult. Fic. 10.—Cixius pini, adult. Fic. 11—Epiptera sp., nymph. Fic. 12—Cyrpoptus reinecket, adult. Fic. 13.—Pentagramma vittatifrons, nymph. Fic. 14—Pentagramma vittatifrons, adult. Fic. 15.—Dictyophora florens, adult. Fic. 16—Bruchomorpha sp., adult. Fic. 17.—Bruchomorpha sp., nymph. Fic. 18—Acanalonia latifrons, adult. Fic. 19.—Lepyronia quadrangularis, nymph. Fic. 20—Lepyronia quadrangularis, adult. PHYLOGENY OF HEMIPTERA—SPOONER PLATE I 54 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE II Cephalo-ventral aspect of the head Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. 21.—M onecophora bicincta, adult. 22.—Tibicen sayt, nymph. 23.—Tibicen sayi, adult. 24.—Ceresa sp., nymph. 25.—Ceresa sp., adult. 26.—Carynota mera, adult. 27.—Agallia constricta, adult. 28.—Oncometopia undata, adult. 29.—Jassus olitorius, nymph. 30.—Jassus olitorius, adult. 31.—Erythroneura comes, adult. 32.—A cinopterus acuminatus, adult. 33.—Lachnus sp., adult. 34.—Pachypsylla celtidis-mamma, adult. 35.—Trialeurodes sp., adult. 55 PHYLOGENY OF HEMIPTERA—SPOONER PLATE II ILLINOIS BIOLOGICAL MONOGRAPHS PLATE III Dorsal aspect of the head . 36.—Unknown fulgorid, nymph. . 37—Acanalonta sp., nymph. . 38.—Liburniella ornata, nymph. . 39—Pentagramma vittatifrons, nymph. . 40.—Bruchomorpha sp., nymph. 5. 41.—Bruchomorpha sp., adult. . 42—Lepyronia quadrangularis, nymph. 3. 43.—Lepyronia quadrangularis, adult. . 44.—Tibicen sayt, nymph. . 45.—Ceresa sp., nymph. s. 46—Ceresa sp., adult. . 47,—Jassus olitorius, nymph. . 48.—Gypona sp., nymph. . 49—Oncometopia undata, adult. . 50.—Lachnus sp., adult. ;. 51—Pachypsylla celtidis-mamma, adult. . 52.—Trioza tripunctata, adult. MN Ww . ole > “se of | ; C iy Ht Sth ; | > KN oC ) a of Cos ss | < 7 ol te @ og. we? f i < ? y | | jo) : | | , 2 x | $ , , / A) : | | | : ‘ a | (3) « pases ay Ca : Fa tere ) : : : : : Y se Q 3 (6° \ | , >) y : ) | = pl bs eo hice OPTS: | eo i | 7 -_ yi = 1 fe Ht 3 Q sy ~S I SS | ) ee . “ on ears \ = an oe ce | (a ; 1 an “ / CS H Ae a I \ é } ( | clans 1 oy > ° \ / ‘ sia ; Og pe ie H | & > y a re) ye BN see Q 1 = / , | is : = secees © ° 7 nel a < H i ° SS : i : m & : ' a : S 52 PLATE ITI S1 58 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. FIc. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE IV Lateral aspect of the head 53.—Otiocerus degeerit, adult. 54—Lamenia sp., adult. 55.—A maloptera uhleri, adult. 56.—Acanalonia sp., nymph. 57.—A canalonia latifrons, adult. 58.—Ormenis pruinosus, adult. 59.—Pelitropis rotatula, adult. 60.—Oliarus vicarius, adult. 61.—Catonia impunctata, adult. 62.—Cixius pini, adult. 63.—Epiptera sp., nymph. 64—Cyrpoptus reineckei, adult. 65.—Pentagramma vittatifrons, adult. 66.—Dictyophora florens, adult. 67.—Bruchomorpha sp., nymph. 68.—Bruchomorpha sp., adult. 69.—Lepyronia quadrangularis, nymph. 70.—Lepyronia quadrangularis, adult. 71—Monecophora bicincta, adult. 59 PHYLOGENY OF HEMIPTERA—SPOONER PLATE IV ILLINOIS BIOLOGICAL MONOGRAPHS PLATE V Lateral and caudal aspects of the head Fic. 72.—Tibicen sayi, nymph, lateral. Fic. 73.—Tibicen sayi, adult, lateral. Fic. 74.—Ceresa sp., nymph, lateral. Fic. 75.—Ceresa sp., adult, lateral. Fic. 76.—Carynota mera, adult, lateral. Fic. 77.—Agallia constricta, adult, lateral. Fic. 78—Gypona sp., nymph, lateral. Fic. 79—Oncometopia undata, adult, lateral. Fic. 80.—Phlepsius excultus, adult, lateral. Fic. 81.—Acinopterus acuminatus, adult, lateral. Fic. 82.—Euscelis bicolor, adult, lateral. Fro. 83.—Jassus olitorius, adult, lateral. Fic. 84.—Erythroneura comes, adult, lateral. Fie. 85.—Lachnus sp., adult, lateral. Fic. 86.—Trialeurodes sp., adult, lateral. Fic. 87.—Otiocerus degeerii, adult, caudal. Fic. 88—Lamenia sp., adult, caudal. Fic. 89—Acanalonia sp., nymph, caudal. Fic. 90.—Acanalonia latifrons, adult, caudal. 61 PHYLOGENY OF HEMIPTERA—SPOONER of of pt 89 90 mp PLATE V 62 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic, Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE VI Caudo-dorsal aspect of the head 91.—Ormenis pruinosa, adult. 92.—Pelitropis rotatula, adult. 93.—Oliarus vicarius, adult. 04.—Catonia impunctata, adult. 95.—Epiptera sp., nymph. 96.—Cyrpoptus reineckei, adult. 97.—Pentagramma vittatifrons, adult. 98.—Dictyophora florens, adult. 99—Bruchomorpha sp., adult. 100.—Monecophora bicincta, adult. 101—Lepyronia quadrangularis, nymph. 102.—Lepyronia quadrangularis, adult. 103.—Carynota mera, adult. 104.—Tibicen sayi, nymph, 105.—Tibicen sayi, adult. 106.—Ceresa sp., adult. 107.—Ceresa sp., nymph. 108—Gypona sp., nymph. PHYLOGENY OF HEMIPTERA—SPOONER 63 b-- PLATE VI ILLINOIS BIOLOGICAL MONOGRAPHS PLATE VII Caudo-dorsal, dorsal, and cephalic aspect of the head Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. 109.—Jassus olitorius, nymph, caudo-dorsal. 110.—Jassus olitortus, adult, caudo-dorsal. 111.—Acinopterus acuminatus, adult, caudo-dorsal. 112.—Euscelis bicolor, adult, caudo-dorsal. 113.—Phlepsius excultus, adult, caudo-dorsal. 114—Oncometopia undata, adult, caudo-dorsal. 115.—Erythroneura comes, adult, caudo-dorsal. 116—Belostoma flumineum, nymph, dorsal. 117—Belostoma flumineum, adult, dorsal. 118—Belostoma flumineum, adult, cephalic. 119.—Belostoma flumineum, nymph, cephalic. 120.—Ranatra americana, adult, cephalic. 121.—Ranatra anvericana, adult, dorsal. PHYLOGENY OF HEMIPTERA—SPOONER = v @ i of 4p ct mi mp 110 L * seit Nae “att of ap’ ¢ ct mi Lh 114 iv (ul i aaazereisl of TH Ne ct mt’ Hara saa 117 ae mp 115 mp pac 116 ac br mp lbr 35 Pc v ac ac pe mp ‘ fr e2 I t ac “\ Pac Ha i t (9jissetessss 119 Ibr Ht HEH srsseeseaen: =~ HEE rit ideseuees pc Ib sas pa /, ac lbr = - @ = Ht Hf segesses : ie Ysa we: HHH = N » => PLATE VII 66 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE VIII Dorsal, ventral, and cephalic aspects of the head Fic Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. . 122.—Ranatra americana, nymph, dorsal aspect. 123—Nepa apiculata, nymph, dorsal aspect. 124.—Nepa apiculata, adult, dorsal aspect. 125.—Pelocoris femoratus, nymph, dorsal aspect. 126.—Pelocoris femoratus, nymph, cephalic aspect. 127.—Pelocoris femoratus, adult, cephalic aspect. 128—Pelocoris femoratus, adult, dorsal aspect. 129.—Notonecta sp., nymph, dorsal aspect. 130.—Notonecta sp., nymph, cephalic aspect. 131—WNotonecta sp., adult, cephalic aspect. 132.—Notonecta sp., adult, ventral aspect. 133.—Corixa sp., nymph, dorsal aspect. 134.—Corixa sp., nymph, cephalic aspect. 135.—Corixa sp., adult, cephalic aspect. 136.—Gerris marginatus, nymph, dorsal aspect. 122 130 PHYLOGENY OF HEMIPTERA—SPOONER ac tr ea br : + rete gears Ht st! t serrr at 1 Pig tans ! \ er : 131 ac ac \ lbr lbr fr fr en oa : pac os ac ac \ ----1_ Ibr 135 & PLATE VIII +4 Hf t i (esssaaees sv Rt fr t um 2 a ¥# mp HH 133 < & iv al : & ‘S{ zs it i\a { + \ pe t y f x pe y pac aes ac ( Bae mp ae Ibr 136 epi 68 Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic, Fic. Fic. Fic. Fic. Fic. ILLINOIS BIOLOGICAL MONOGRAPHS PLATE IX Dorsal and cephalic aspects of the head 137.—Gerris marginatus, adult, dorsal aspect. 138.— Gerris marginatus, nymph, cephalic aspect. 139.—Gerris marginatus, adult, cephalic aspect. 140.—Rhagovelia obesa, nymph, dorsal aspect. 141.—Rhagovelia obesa, nymph, cephalic aspect. 142.—Rhagovelia obesa, adult, cephalic aspect. 143.—Mesovelia bisignata, adult, dorsal aspect. 144.—Hydrometra martini, adult, dorsal aspect. 145 —Hydrometra martini, adult, cephalic aspect. 146.—Naeogeus durmeistert, adult, cephalic aspect. 147.—Ochterus americanus, adult, cephalic aspect. 148.—Gelastocoris sp., nymph, cephalic aspect. 149.—Ochterus americanus, nymph, cephalic aspect. 150.—Gelastocoris sp., adult, cephalic aspect. 151—Cimex lectularius, nymph, cephalic aspect. 69 PHYLOGENY OF HEMIPTERA—SPOONER ieee ae aagece 139 137 epi 142 141 mt . 144 140 lbr 147 es epi ea as 150 epi PLATE IX ILLINOIS BIOLOGICAL MONOGRAPHS PLATE X Dorsal and cephalic aspects of the head Fic. 152—Cimex lectularius, adult, cephalic aspect. Fic. 153—Cimex lectularius, nymph, dorsal aspect. Fic. 154—Cimex lectularius, adult, dorsal aspect. Fic. 155.—Lamprocanthia sp., nymph, cephalic aspect. Fic. 156.—Lamprocanthia sp., adult, cephalic aspect. Fic, 157.—Triphleps insidiosa, nymph, dorsal aspect. Fic. 158.—Triphleps insidiosa, adult, dorsal aspect. Fic. 159.—Sinea sp., nymph, cephalic aspect. Fic. 160.—Sinea sp., nymph, dorsal aspect. Fic. 161.—Sinea sp., adult, dorsal aspect. Fic. 162.—Emesa brevipennis, nymph, dorsal aspect. Fic. 163—Emesa brevipennis, adult, dorsal aspect. Fic. 164.—Melanolestes abdominalis, adult, dorsal aspect. Fic. 165.—Nabis subcoleoptratus, nymph, dorsal aspect. Fic. 166.—Nabis subcoleoptratus, adult, dorsal aspect. Fic. 167.—Nabis subcoleoptratus, nymph, cephalic aspect. PHYLOGENY OF HEMIPTERA—SPOONER 71 PLATE X 72 Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XI Dorsal and cephalic aspects of the head 168.—Systelloderus biceps, nymph, dorsal aspect. 169.—Systelloderus biceps, adult, dorsal aspect. 170.—Ceratocombus vagans, nymph, dorsal aspect. 171.—Ceratocombus vagans, adult, dorsal aspect. 172.—Miris dolobratus, nymph, dorsal aspect. 173.—Miris dolobratus, adult, cephalic aspect. 174—Adelphocoris rapidus, adult, cephalic aspect. 175.—Ischnodemus falicus, nymph, dorsal aspect. 176.—I schnodemus falicus, adult, dorsal aspect. 177.—Ischnodemus falicus, adult, cephalic aspect. 178.—Euryophthalmus succinctus, nymph, dorsal aspect. 179.—Euryophthalmus succinctus, nymph, cephalic aspect. 180. —Euryvophthalmus succinctus, adult, dorsal aspect. 181.—Myodochus serripes, nymph, dorsal aspect. 182—Mvyodochus serripes, adult, dorsal aspect. PHYLOGENY OF HEMIPTERA—SPOONER 73 175 PLATE XI 74 Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XII Dorsal and cephalic aspects of the head 183.—M yodochus serripes, adult, cephalic aspect. 184.—Neides muticus, nymph, cephalic aspect. 185.—Neides muticus, adult, cephalic aspect. 186.—Neides muticus, nymph, dorsal aspect. 187. —Neides muticus, adult, dorsal aspect. 188.—Corizus sp., nymph, dorsal aspect. 189.—Corizus sp., adult, cephalo-dorsal aspect. 190. —Harmoestes reflexulus, adult, dorsal aspect. 191.—Alydus sp., nymph, cephalo-dorsal aspect. 192 —Alydus sp., adult, cephalo-dorsal aspect. 193.—Leptocoris trivittatus, nymph, dorsal aspect. 194.—Leptocoris trivittatus, adult, cephalic aspect. 195 —Leptocoris trivittatus, adult, dorsal aspect. 196.—Piesma cinerea, adult, dorsal aspect. 197.—Corythuca ciliata, nymph, dorsal aspect. 198—Corythuca ciliata, nymph, cephalic aspect. PHYLOGENY OF HEMIPTERA—SPOONER 75 PLATE XII 76 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XIII Dorsal and cephalic aspects of the head 199.—Corythuca ciliata, adult, cephalic aspect. 200.—Phymata sp., nymph, dorsal aspect. 201.—Phymata sp., adult, dorsal aspect. 202.—Phymata sp., nymph, cephalic aspect. 203.—Phymata sp., adult, cephalic aspect. 204.—Aneurus sp., nymph, cephalic aspect. 205.—Aneurus sp., adult, cephalic aspect. 206.—Aneurus sp., nymph, dorsal aspect. 207.—Aneurus sp., adult, dorsal aspect. 208—Brochymena sp., nymph, dorsal aspect. 209.—Brochymena sp., adult, dorsal aspect. 210.—Stethaulax marmoratus, adult, dorsal aspect. 211.—Corimelaena sp., adult, dorsal aspect. 212.—Cyrtomenus nurabilis, adult, dorsal aspect. PHYLOGENY OF HEMIPTERA—SPOONER 77 fr @ =, ® ac pac ' P| m H b 199 - } lbr 202 mp : 206 aes fas nes Klbr ra : ae jo oar : 4 1 k-4 1 Hl af i A Ne H pe \ ) \ H \ { pac / ( ac aat ac pac aly ; ay 209 207 V4! 208 ae te. Te -" O o~ Ho i re pe y © oF ac ac pac pac ac pac 210 211 212 PLATE XIII 78 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XIV Lateral aspect of the head . 213—Belostoma flumineum, nymph. . 214—Belostoma flumineum, adult. . 215.—Ranatra americana, adult. . 216—Ranatra americana, nymph. . 217—Nepa apiculata, nymph. . 218 —Nepa apiculata, adult. . 219.—Pelocoris femoratus, adult. . 220.—Pelocoris femoratus, nymph. . 221.—Gerris marginatus, nymph. . 222.—Notonecta sp., nymph. . 223—Notonecta sp., adult. ;. 224—Corixa sp., nymph. . 225.—Corira sp., adult. . 226—Gerris marginatus, adult. . 227.—Rhagovelia obesa, nymph. . 228.—Rhagovelia obesa, adult. . 229.—Naeogeus burmeistert, adult. 5. 230.—Mesovelia bisignata, adult. . 231.—Hydrometra martini, adult. 79 PHYLOGENY OF HEMIPTERA—SPOONER Seses fie t+ 230 231 mp . bu : fir TE epaaeae PLATE XIV ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XV Lateral aspect of the head 232.—Ochterus americanus, nymph. 233—Ochterus americanus, adult. 234.—Gelastocoris sp., nymph. 235.—Cimex lectularius, nymph. 236.—Gelastocoris sp., adult. 237.—Cimex lectularius, adult. 238.—Lamprocanthia sp., adult. 239.—Triphleps insidiosa, nymph. 240.—Triphleps insidiosa, adult. 241.—Sinea sp., nymph. 242.—Sinea sp., adult. 243.—Emesa brevipennis, nymph. 244—Emesa brevipennis, adult. 245.—Melanolestes abdominalts, adult. 246.—Nabis subcoleoptratus, adult. 247.—Nabis subcoleoptratus, nymph. 248.—Systelloderus biceps, nymph. 249.—Systelloderus biceps, adult. 250 —Ceratocombus vagans, nymph. PHYLOGENY OF HEMIPTERA—SPOONER 81 hh ©. 4) i H ¢ | mc itt \ Rog H \ ; an @ i aes ac mp\ acy } lbr br 232 Sssse > setae: iit ft tH tt HH + ‘br pac af =P oc PLATE XV 82 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XVI Lateral aspect of the head . 251.—Ceratocombus vagans, adult. . 252—Miuris dolobrata, adult. 3, 253—Adelphocoris rapidus, adult. 5. 254.—Ischnodemus falicus, nymph. . 255. —Ischnodemus falicus, adult. . 256.—Euryophthalmus succinctus, nymph. . 257 —Euryophthalmus succinctus, adult. . 258.—M yodochus serripes, nymph, . 259.—Myodochus serripes, adult. . 260.—Neides muticus, nymph. . 261—Neides muticus, adult. 3. 262.—Corisus sp., nymph. . 263.—Alydus sp., adult. . 264—Alydus sp., nymph. . 265 —Corizus sp., adult. PHYLOGENY OF HEMIPTERA—SPOONER 83 PLATE XVI 84 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XVII Lateral aspect of the head ;. 266.—Harmoestes reflexulus, adult. . 267.—Leptocoris trivittatus, adult. . 268.—Leptocoris trivittatus, nymph. . 269.—Piesma cinerea, adult. . 270—Corythuca ciliata, nymph. . 271.—Corythuca ciliata, adult. _ 272.—Phymata sp., nymph. . 273.—Phymata sp., adult. . 274.—Aneurus sp., nymph. . 275.—Aneurus sp., adult. . 276.—Brochymena sp., nymph. . 277.—Brochymena sp., adult. . 278.—Corimelaena sp., adult. _ 279.—Stethaulax marmoratus, adult. ;. 280.—Cyrtomoenus mirabilis, adult. PHYLOGENY OF HEMIPTERA—SPOONER 8&5 PLATE XVII 86 ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XVIII Ventral and caudal aspects of the head . 281.—Belostoma flumineum, nymph, ventral aspect. . 282 —Belostoma flumineum, adult, ventral aspect. G. 283.—Ranatra americana, nymph, ventral aspect. . 284—Ranatra americana, adult, ventral aspect. . 285 —Nepa apiculata, nymph, ventral aspect. . 286—Nepa apiculata, adult, ventral aspect. G. 287—Pelocoris fenvoratus, nymph, ventral aspect. 3. 288.—Pelocoris femoratus, adult, ventral aspect. ;. 289.—Notonecta sp., adult, caudal aspect. 290.—Cortra sp., adult, caudal aspect. . 291.—Corixa sp., nymph, caudal aspect. . 292 —Gerris marginatus, nymph, ventral aspect. . 293—Gerris marginatus, adult, ventral aspect. 281 PHYLOGENY OF HEMIPTERA—SPOONER oc of ou i) \ i r) tr) ic \P of (ica f ete a ‘el ta H vi a oe @ mp NW +4 (pies bo ee \ 282 gu { @ he 285 af SS PLATE XVIII oc of wt? m4 , aa ir a ‘ ic q mp s ‘: ‘ \ 283 l®@® 87 oo of gu £ 4 i Oi © \ : / / mp oc gu \ y af @& 8& Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. ILLINOIS BIOLOGICAL MONOGRAPHS PLATE XIX Ventral and caudal aspects of the head 294.—Rhagovelia obesa, adult, ventral aspect. 295.—Mesovelia bisignata, adult, ventral aspect. 296 —Hydrometra martini, adult, ventral aspect. 297. —Naeogeus burmeisteri, adult, ventral aspect. 298.—Gelastocoris sp., nymph, ventral aspect. 299._—Gelastocoris sp., adult, ventral aspect. 300.—Gelastocoris sp., nymph, caudal aspect. 301.—Gelastocoris sp., adult, caudal aspect. 302.—Ochterus americanus, adult, ventral aspect. 303—Ochterus americanus, nymph, caudo-ventral aspect. 304.—Ochterus americanus, adult, caudal aspect. 305.—Lamprocanthia sp., nymph, caudal aspect. 306.—Cimex lectularius, nymph, ventral aspect. 307.—Cimex lectularius, adult, ventral aspect. 308.—Lamprocanthia sp., adult, caudal aspect. 309.—Triphleps insidiosa, adult, ventral aspect. 310.—Triphleps insidiosa, nymph, ventral aspect. 89 PHYLOGENY OF HEMIPTERA—SPOONER 295 \ >, ac \pac 294 300 298 Ses 299 304 307 of 303 i mp of 305 302 = ait aan ibaa HE A Bee HE a & tec, mp 310 mp 309 mp |308 PLATE XIX 90 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XX Ventral aspect of the head 311.—Sinea sp., nymph. 312.—Sinea sp., adult. 313.—Emesa brevipennis, nymph. 314—Emesa brevipennis, adult. 315.—Melanolestes abdominalis, adult. 316.—Nabis subcoleoptratus, nymph. 317.—Nabis subcoleoptratus, adult. 318.—Systelloderus biceps, adult. 319.—Ischnodemus falicus, nymph. 320.—Ischnodemus falicus, adult. 321.—Euryophthalmus succinctus, nymph. 322 —Euryophthalmus succinctus, adult. 323.—M yodochus serripes, nymph. 324.—Myodochus serripes, adult. 325.—Neides muticus, nymph. 326—Neides muticus, adult. 327.—Corizus sp., nymph. 328.—Corizus sp., adult. ol PHYLOGENY OF HEMIPTERA—SPOONER gu mp 315 311 317 X PLATE X 92 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XXI Ventral aspect of the head 329. —Harmoestes reflexulus, adult. 330.—Alydus sp., nymph. 331.—Alydus sp., adult. 332.—Leptocoris trivittatus, nymph. 333.—Leptocoris trivittatus, adult. 334.—Piesma cineria, adult. 335.—Corythuca ciliata, nymph. 336.—Corythuca ciliata, adult. 337.—Phymata sp., nymph. 338.—Phymata sp., adult. 339.—Aneurus sp., nymph. 340.—Aneurus sp., adult. 341.—Brochymena sp., nymph. 342.—Brochymena sp., adult. 93 PHYLOGENY OF HEMIPTERA—SPOONER of 332 \br of If 35 Ibr PLATE XXI 04 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. PLATE XXII Ventral aspect of the head 343.—Cyrtomoenus mirabilis, adult. 344.—Stethaulax marmoratus, adult. 345.—Corimelaena, adult. Anteclypeus and labrum, lateral aspect Fic. Fic. Fic. Fic. FIc. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. 346.—Otiocerus wolfi, adult. 347.—Belostoma flumineum, adult. 348.—Euschistus tristigmus, adult. Mandible and lever 349.—Corixa sp., adult. 350.—Otiocerus degeerii, adult. a. Marginal view. 351.—Lepyronia quadrangularts, adult. a. Marginal view. 352.—Tibicen sayt, adult. 353.—Oncometopia undata, adult. 354.—Belostoma flumineum, nymph. 355.—Belostoma flumineum, adult. 356.—Ranatra americana, adult. 357.—Melanolestes abdominalis, adult. 358.—Pelocoris femoratus, adult. 359—Notonecta sp., adult. 360.—Gerris marginatus, adult. 361.—Rhagovelia obesa, adult. 362.—Mesovelia bisignata, adult. 363—Hydrometra martim, adult. 364.—Naeogeus burmeisteri, adult. PHYLOGENY OF HEMIPTERA—SPOONER 95 354 / 355 | PLATE XXII 96 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XXIII Mandible and lever 365.—Ochterus viridifrons, adult. 366.—Ochterus americanus, adult. 367.—Cimex lectularius, adult. 368.—Gelastocoris sp., adult. 369.—Pentocora sp., adult. 370.—Sinea sp., adult. 371.—Emesa brevipennis, adult. 372.—Miris dolobratus, adult. 373.—Adelphocoris rapidus, adult. 374.—Ischnodemus falicus, adult. 375 —Euryophthalmus succinctus, adult. 376.—M yodochus serripes, adult. 377 —Neides muticus, adult. 378.—Jalysus spinosus, adult. 379.—Corizus sp., adult. 380.—Alydus sp., adult. 381.—Anasa tristis, adult. PHYLOGENY OF HEMIPTERA—SPOONER 97 at at 7° 174 ieeen VT" PLATE XXIII 368 98 ILLINOIS BIOLOGICAL MONOGRAPHS Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. Fic. PLATE XXIV Mandible and lever 382.—A canthocephala terminalis, adult. 383.—Piesma cinerea, adult. 384.—Corythuca ciliata, adult. 385.—Phymata sp., adult. 386.—Aneurus sp., nymph. 387.—Aneurus sp., adult. 388.—Cyrtomoenus mirabilis, adult. 389.—Stethaulax marmoratus, adult. 390. —a. Euschistus servus, adult, lever. b. Euschistus euschistoides, adult, lever. c. Euschistus tristigmus, adult, lever. 391.—a. Euschistus tristigmus luridus, adult, lever. b. Euschistus servus variety, adult, lever. Labium 392.—Gerris remigera, adult, lateral aspect. 393.—Ochterus americanus, adult, lateral aspect. 394.—Gelastocoris sp., adult, lateral aspect. 395.—Ceratocombus vagans, adult, lateral aspect. 396.—Pentacora sp., adult, lateral aspect. 397.—Miris dolobratus, adult, lateral aspect. 398.—A delphocoris rapidus, adult, lateral aspect. PHYLOGENY OF HEMIPTERA—SPOONER 99 392 394 at at at \) Lu LL at a at b 391 \ < 395 396 397 398 PLATE XXIV Acanalonia, 14 Acanalonia latifrons, 14, 17 Acinopterus acuminatus, 14, 20 Aleyrodidae, 22, 24, 43 Alydidae, 40, 44 Alydus sp., 31, 32, 33, 35 Amaloptera uhleri, 14, 17 Amphibicorises, 38, 39, 43, 44 Aneurus sp., 27, 28, 36 Anonycha, 38 Anteclypeus, 15, 16, 28 Anthocoridae, 39, 40, 41, 43 Aphididae, 21, 23, 24, 43 Aphrophorinae, 43 Apis, 19 Apterygota, 19 Aradidae, 35, 40, 41, 44 Auchenoryncha, 22, 24 Belostoma, 35, 36 Belostoma flumineum, 30, 31, 33 Belostomatidae, 31, 39, 41 Benacus, 33 Blatta, 19 Brochymena sp., 27, 28, 30, 31, 33, 35 Bruchomorpha, 14, 17 Bucculae, 30, 40 Carynota mera, 15, 17, 20 Catonia impunctata, 15, 17 Caudal aspect of the head, Homoptera, 18 Ceratocombus vagans, 8, 31 Cercopidae, 19, 22, 24, 43 Ceresa, 20 Cicadellidae, 22, 23, 24, 43 Cicadidae, 20, 22, 23, 43 Cimex lectularius, 26, 28, 29, 31 Cimicidae, 31, 39, 40, 43 Cixiidae, 24 Clypeal region, Homoptera, 15 Heteroptera, 28 Coccidae, 22, 43 Coreidae, 41 Corimelaena sp., 30 Corimelaenidae, 40, 44 Corixa sp., 27, 29, 31, 36 Corixidae, 31, 38 Corizidae, 40, 44 Corizus sp., 30 INDEX Corpotentorium, 19, 20 Corydalis, 15 Corythuca ciliata, 30, 31 Cryptocerata, 28, 38 Cryptostemmatidae, 40, 44 Cyarda melichari, 14, 17 Cydnidae, 40, 44 Cyrtomenus mirabalis, 30 Dictyophora florens, 14 Diptera, 18 Emesa brevipennis, 27, 28, 31, 35 Emesidae, 40 Enicocephalidae, 40, 44 Ephemerida, 19 Epipharynx, Homoptera, 18 Heteroptera, 31 Epiptera, 14, 17 Erythroneura comes, 14, 20 Eugereon, 11, 25 Euryophthalmus succinctus, 27, 32 Euscelis bicolor, 17, 20 Euschistus, 37 Euschistus tristigmus, 37 Frons, Homoptera, 14 Heteroptera, 28 Fulgoridae, 12, 13, 22, 23, 24, 37, 43 Gelastocoris sp., 29, 31, 36 Generalized head, 10 Geocorises, 38, 40, 43, 44 Gerridae, 32, 37, 39 Gerris marginatus, 27, 32, 33, 36 Gerris remigus, 37 Gula, 18, 32 Gymnocerata, 28, 38 Gypona, 14 Harmoestes reflexulus, 32 Hemimaxillae, 17 Hemiodoecus leai, 21 Heteroptera, 11, 23, 24 Homoptera, 11 Hydrobiotica, 38 Hydrocorises, 38, 39, 40, 43 Hydrometra martini, 30 Hydrometridae, 39, 41 Hypopharynx, 18, 19 100 INDEX 101 Ischnodemus falicis, 28 Issidae, 23 Jassus olitorius, 14, 20 Jugae, 27 Labial suture, 17 Labium, Heteroptera, 34 Homoptera, 21 Labrum, Heteroptera, 31 Homoptera, 18 Labrum-epipharynx, 18 Lachnini, 21 Lachnus, 14 Lamenia, 14, 16 Lamprocanthia, 26, 29, 30, 31, 34 Leptocoris trivittatus, 32 Lepyronia quadrangularis, 14, 15, 17, 19, Ze 25 Liburniella ornata, 14 Lygaeidae, 41, 44 Mandibular levers, 21, 35 Maxillary levers, 22 Maxillary plates, Heteroptera, 30 Homoptera, 22 Maxillary process, 18 Maxillary setae, 37 Maxillary suture, 17 Melanolestes abdominalis, 31, 33, 35, 36 Membracidae, 20, 22, 24, 43 Mesovelia bisignata, 36 Mesoveliidae, 32, 39, 41 Metatentoria, 17, 19, 20 Metatentorina, 18 Microphysidae, 41 Miridae, 40, 44 Miris dolobratus, 31 Monecophora bicincta, 14, 17, 19, 23 Myodochus serripes, 28, 32 Myriapoda, 19 Nabidae, 31, 40, 44 Nabis subcoleoptratus, 27, 30, 31, 35 Naeogeidae, 32, 39, 41 Naeogeus burmeisteri, 32, 36 Naucoridae, 29, 31, 39, 43 Naucoris, 35 Naucoris cimicoides, 7 Neides muticus, 28, 29, 30, 31, 32, 35 Neididae, 40, 41, 44 Nepa, 35 Nepidae, 39, 41 Nerthridae, 29, 32, 39, 41, 44 Notonecta sp., 29, 30, 31, 35, 36 Notonectidae, 29, 31, 39, 43 Ochteridae, 29, 32, 39, 41, 44 Ochterus americanus, 29, 33, 36, 37 Ochterus viridifrons, 36, 37 Odonata, 19 Odontoidea, 18 Oecleus borealis, 13, 15 Oncometopia undata, 14, 20, 23 Onychiopoda, 38 Ormenis pruinosa, 14 Otiocerus degeerii, 12, 14, 15, 16, 21, 29, 37 Otiocerus wolfii, 16, 29, 37 Pachypsylla celtidis-mamma, 14, 21, 22 Pagiopoda, 38 Paraclypeus, 15, 16, 28 Pelitropis rotatula, 14, 17 Pelocoris, 35, 36 Pelocoris femoratus, 29, 30, 31, 33 Peloridiidae, 21 Peltocephala, 38 Pentagramma vittatifrons, 14 Phlepsius excultus, 20 Phylogeny, Heteroptera, 37 Homoptera, 22 Phymata, 29, 30, 33, 35 Phymatidae, 40 Piesma cineria, 35 Piesmidae, 40, 41, 44 Poekillopteridae, 23 Polyneura, 38 Postgenae, 17 Postclypeus, 15, 16, 28 Postoccipital suture, 17 Pretentorium, 19, 20 Pristhesancus papuensis, 29 Protohomoptera, 23 Psylla mali, 7, 22 Psyllidae, 22, 23, 24, 43 Pterygota, 19 Pyrrhocoridae, 40, 41, 44 Pyrops candelaria, 21 Ranatra, 35 Ranatra americana, 30, 33 Reduviidae, 31, 40, 44 Reduvius personatus, 28 Rhagovelia obesa, 32, 36 102 ILLINOIS BIOLOGICAL MONOGRAPHS Saldidae, 25, 31, 34, 40, 41 Tettigonidae, 43 Sandaliorrhyncha, 38, 43 Thaumasticoridae, 41 Scolops, 13 Thyreocoridae, 41 Scutelleridae, 41 Tibicen sayi, 14, 15, 20, 22, 23 SINEA SREP Gunes Tingitidae, 31, 40, 44 Sternorhyncha, 22 Trachalopeda,. 36 Stethaulax marmoratus, 30, 31, 33, 35 Supratentorium, 19, 20 Systellodorus biceps, 31, 35 Trioza tripunctata, 14 Triphleps insidiosa, 26, 27, 31, 33, 34 Tentorium, Heteroptera, 33 Veliidae, 32, 39, 41 Homoptera, 18 Vertex, Heteroptera, 27 Termatophylidae, 41 Homoptera, 13 UNIVERSITY OF ILLINOIS-URBANA 570.51LL c001 ILLINOIS BIOLOGICAL MONOGRAPHS$URBANA “HANLNUULLALL 30112 009416469