266 Macteay Memoria Vouume. 
supplementary male organs are known in the genus except papille of another 
character near the anus. 
There is an interesting dorsal organ on the head,—of unknown significance. It 
will be noticed in the description of the species in which it has been observed. 
Keay. 
Pharynx with one or two large teeth. 
Tail end (female at least) encircled by a few conspicuous rings...... ..........06+ . Ll. viviparus. 
Tail end not so encircled. 
Length of the female not exceeding 1: mm, 
Body slender (little more than 2°6 %); neck long (23° %) ........... eae 2. parvus. 
Body not so slender (3 / and over) ; neck shorter (15° % to 22° %). 
Female sexual organs asymmetrical (single). 
Gisophacusell Giese ee erea eerie see: re sO sea oswe Ses eae 3. monhysteroides. 
Giisophiagus: 20Gb samawasasstatelscce nce sean vereslemeneincet enon atceteene seer eee 4. minor. 
Female sexual organs double and symmetrical. 
Reflexed ovaries crossing each other..........0...sccecee ceeeneee oe 5. filicaudatus. 
Reflexed ovaries not crossing. 
C&sophagus swollen just behind the pharynx................ 6. australis. 
Cisophagus not so swollen, 
Body “4mm Ong s.ccscessecctas oo cesr acess ee doecnearcases: 7. minima. 
Body ‘75 mm. long...... ~“Agcnn danidt.lago mdobpooupodbdnsen one 8. graminum.* 
Length of the female 1:5 mm. or more. 
Throat or pharynx with two equally well developed teeth................6. 9. fluviatilis. 
Throat or pharynx with only one well developed tooth, 
Tail about half as long as the WOrM.............esecccesecececeeereenes « 10. trichuris. 
Tail about one-third as long as the WOrm............cceeeceeseeeeeeeeece 11. striatus. 
Tail about one-seventh (15 %) as long as the worm. 
IBY MEGS ani th geese fea: aor eendoescacnobecdstecacoscnasees, ceqcaciorin soe 12. macrodon. 
Den gthy 2 Go22: Simms. mayssascicecscetdsecete sce fase tetas ice 13, rivalis. 
Pharynx with only much less well developed teeth at the base, 
Hemaleysexual organs single, asymmetrical... .cnscceccceresseeccee-eeeenceeesrcianenacener 14. gracilis. 
Female sexual organs double, symmetrical. 
Throat or pharynx shallow (half as deep as wide). 
Idpsidishinetrs pharynsmob Striated. weranekesccsesces stent adeeeeerseness ane 15. inermis. 
inpshindistinet. pharynx istriated a .sk <2 secpe se ese erences eseeeodecee settee 16. similis, 
Throat or pharynx as deep as wide, with small teeth at the base, 
Length exceeding 1:mm. 
Tail nearly one-third (30 %) as long as the worm..........-.......6005 17. longicauda. 
Tail only one-fifth (16 to 20 %/) as long as the worm. 
NC Le ree ae oc char conc uceacocnoghc 26 anuGUR dante rac ER EBROP ep eracacac seo 18. filrformis. 
Widthrexceedingliiir/cermrcausadtneteter coe oosssce ichiede no eearriens 19. albus, 
* The unknown female of graminum is assumed to have double and symmetrical sexual organs not crossing. 
