rate median pairs of tliolastDiii.-iliils i-miM liarillv Iimvc ariscii 

 from any known ascariiloid. 



In cephalic papillary arranKi'inout ascariilciiil.s show jirac- 

 tically no diversity but in laliial developments diversity is 

 marked. 



Members of the Cosinoeereidae (Cosmocriciuilis iliduic), 

 Ileterakinae {H< IrraVi.s- naUiiiiif) and Aseariilidae (Axcaris 

 liinibriCDidis) all have three larRe liiis. Tn addition to the lips 

 tliere may l)e ixisteriorly directed cuticular cordons (Aspido- 

 ilfia and nrtn-oc)iiUiis, Ileterakinae and Anisakinae resp.) and 

 between the lips there may be interlabia (I'orri>ciucnm and 

 Piiraxriiri.i, Anisakinae and Ascaridinae resp.). The lips, them- 

 selves, may bear denticles on their internal surfaces (Porro- 

 ciiiriim, Ascaris) ; the apical lobes may be separated from the 

 basal loites by grooves {Parascdris) \ ;nid the labial l)ulp may 

 assume dix'erse forms which .are considered spi'cilic ( PoJydcl- 

 phis qiiO(lrici)nii.i and P. hiidiUicrli) . Members of the Subu- 

 lurinae differ from other ascaridoids in that the lips are 

 reduced to apical lobes bearing only the internal circle of 

 papillae and there may be three (Suhiiliira distans) si.x, or 

 more api)arent lobes. The grossly twelve lobed oral opening 

 of Aiildiiocrphahis pcrtimclis is Interpreted as having ludiments 

 of six lips (the apical lobes) separated by si.\ interlabia. 

 Within the Kathlaniidae all manner of labial multiplicity is 

 known, the genus Spcctiitux being characterized as Ijaving six 

 lips, SpiidiioKra as having three lips, Kalhhinia with about 

 16 labial divisions and f'i.ssoplii/Jiis with a bilaterally syuinietric 

 head. Of these only Spironoura and Cissophyltis have been 

 carefully studied. In Spironoura the lips are essentially as- 

 caroid with the apical lobes separated from the basal by 

 grooves. In Ci^sophylus ro.ieiis the dorsal lip is reduced, and 

 transformed into a three pronged odonfium while the subven- 

 tral lips are massive and dentate. 



C.\M.VLL.\NINA. The .suborder Camallanina (Fig. .'18) differs 

 from the Rhabditina, Strongylina and Ascaridoidea in that 

 ventrolateral papillae are entirel.v unknown. Well developed 

 lips are never present but rudiments of lips or lateral jaws 

 may occur. 



Caniallaiioidea. Most of the members of this superfaniily 

 have no lips but instead two lateral ,iaws. However, the gen- 

 era Omiia and Uaploiirma (Cucullanidae) as described by 

 Hsii (1933) and the genus Procamiillniuis as described by Li 

 (193.1) preserve a less specialized condition. In Omcia six 

 labial rudiments (apical lolies) are present, in Uaplnncma 

 lijis are absent and in ProcamaUaniis the oral opening is 

 hexagonal. The internal circle is in all in.stances reduced in 

 size and the external circle represented by four papillae 

 (duplex in Cucullanidae and simple in Camallanidae). 



Vraciincnhndca. Dracunculoids are devoid of both lips and 

 jaws, the rounded oral opening being surrouniled by a very 

 thin circunioral membrane external to which there may (Dra- 

 ciitwiiliis, Avoiserpens) or may not (Philomeira, ^[icroph•ll}■a) 

 be a cutieularized circunioral elevation. The internal circle 

 is well developed (a more iirimitive condition than in the 

 Camallanoidea) and so also are the eight members of the ex- 

 ternal circle. In Micropleiiia and PhiUnnctrii all of the papil- 

 lae remain distinct while in Draciinculiis and Avioserpen.i the 

 medians of the external circle are partially fused. In Dra- 

 ciinriiliis the internodorsals and internovenfrals fuse in the de- 

 velopment of the female while the male retains the generalized 

 condition. Members of the Dracunculidae also have a thickened 

 cuticular helmet which projects anteriorly forming the cir- 

 cunioral elevation and posteriorly so as to surround the an 

 terior end of the esophagus. 



SpiRt'RlN.\. Like the Camallanina, this suborder contains no 

 forms with ventrolateral cephalic papillae and true lips, if 

 present, are represented only by rudimentary apical lobes. 

 The first superfaniily Spiruroidea shows a marked tendency 

 toward the formation of false lips, p.iciidiilabia, developed 

 from the prorhabdicms of the stoma while the second super- 

 family, Filarioidea, is characterized by the absence of both 

 lil's ami pseudolabia. In their place there may be various 

 types of Labial structures. Within the entire suborder the 

 internal circle of papillae is reduced, rudimentary or appar- 

 ently absent. 



Spirurindra. The majority of .spiruroids (Fig. .",S) have two 

 lateral i)seudolabia but there is one exceptional group, the 

 Thelaziidac. This group is apjiarently the most i>rimitive of 

 the superfaniily and within it the development of pseudolabia 

 is reproduced. The Thelaziinae, Spirocercinae, and Ascarop- 

 sinae contain forms with a rounded to hexagonal oral opening, 

 the hexagonal form apparently corresponding to rudimentary 

 ai)ical lolies of six original lips. The internal circle of papil 

 lae is slightly reduced in all forms except Physoccphaliis in 

 which it is rudimentary. The externodorsals and externoven 



Fio. 56. 



Cephalic regions in the Strongylina. A-E — Strongjlidae. F-H — 

 Synganiidae. 1 — Ancylostomatidae. J — Diaphanocephalidae. K — 

 Cloacinidae. L-P — Triohostrongylidae. Q-R — Pseudaliidae. S-T — 

 Metastrongylidae. A — Slioni/i/lus equinus : B — ilurshidia faleifern ; C — 

 CyUndruitharyiuc rhotlesiensis ; 1) — Oesophagoatomum denlntum ; E — 

 Cyelirocj/clus insiffne. P — Si/ngamus trachea; G — Delelrnrrphalua 

 dfmidiatuK: H — Stepfianurus dentatuti: I — \ecator amfricanua : J — • 

 Kttlicephaltiit sp.; K — Zoninltiimus Helifera; h — Amidostomum cyngi; 

 M — Epoiiiifliontowlim unrinalum ; N — Allintoiihius ngctireius ; O — 

 Cheiropteroneiua glohocephala ; P — Tncholeipfrin penrHfi; Q — FilarioP' 

 Bis arntnr; R — Sfi'ntirus iiiinor; .S — DU'tgocaulus filaria; T — Mrta- 

 stronmihiK ehmgalii.1. B — After Witenburg, 1925, Parasit. v. 17(3). 

 C — '.After Yorke & Maplp.stone, 1926. Nematode para.'iites of vertebrates. 

 I^-T.\fter Wehr. li):i:i, J. Wash. Ac-ad. Sc, v. 23(18): 391-396. M — 

 After Wetzel, 1!131, Proe. I". S. Nat. Mus. (2864) v. 78(21): 1-10. 

 Q— After Welir, 1935, J. Wash. Acad., Sc, v. 25(9). Remainder 

 original. 



59 



