When there is a reduction to one ovary as in heligmo- 

 somes (Heligmosomum laeve) there is a single ovejector 

 having parts identical with the paired structure (Fig. 

 117 G). 



The unspecialized sector of each uterus in Oesophagos- 

 tomum consists of two rows of cells (Fig. 122 S) exhibit- 

 ing possible glandular activity and a distinct bacillary 

 layer. At its connection with the infundibulum the num- 

 ber of cells in a cii'cumference is increased from two 

 to six (Fig. 122 R). In practically all cases the ovaries 

 are greatly elongated due to an extensive growth zone. 



Ascaridinu. Within the Ascaridina, vulva position varies 

 from anterior to the bas« of the esophagus (Protrellus 

 kiinkeli. Fig. 116 K) to practically anal (preanal in 

 Aorunis agile, actually into the rectum in Rondonia ron- 

 doni 108 L). As in the Strongylina, there is usually a 

 well-developed, muscular ovejector, particularly in the 

 Oxyuroidea. The vagina vera is always elongated, usually 

 tubular in the Oxyuroidea; and with the unpaired vagina 

 uterina composes the ovejector. The internal structure 

 of the vagina vera has been described (p. 141). 



For all the marked specialization in ovejector forma- 

 tion, the superfamily Oxyuroidea contains some repre- 

 sentatives which closely approach the free-living nemas. 

 In practically all parasitic nemas the ovaries are filiform 

 with an elongated growth zone. This is true of the 

 majority of oxyuroids and ascaroids as well, 'but in the 

 families Atractidae and Oxyuridae there ai-e several 

 examples with short tapering ovaries, and these forms, 

 but for the vagina, might easily be mistaken for rhabdi- 

 toids. Tachygonetria vivipara (Pharyngodoninae) typi- 

 fies the amphidelphic organization while Heth juli (Ran- 

 somnematinae) typifies the prodelphic, didelphic, and 

 Labidurus gulosa ( Labidurinae) and Atractis dactyluris 

 the prodelphic, monodelphic condition. Among the oxyur- 

 ids vulvar position is extremely variable and the uteri 

 ai-e often parallel. In Dermatoxys veligera (Fig. 117 W), 

 Oxyuris equi (Fig. 117 V) and Syphacia obvelata the 

 vulva is shifted anteriad while the greatly elongated 

 vagina uterina connects at the po.sterior end with the 

 anteriorly directed utsri. Seurat (1920) interpreted this 

 formation as modified prodelphy but Vogel (192.5) has 

 shown that on the basis of young specimens (Fig. 159 K), 

 Syphacia and Dc-rmatoxys must be considered primarily 

 aynphidelphic like Tachygonetria mviparu. Similarly Pro- 

 trellus kiinckeli is an amphidelphic thelostomatid example 

 of vulvar shifting, with elongation of vagina uterina; 

 Cephalobellus papiUiger and Hystrignathus rigidus ex- 

 emplify the standard condition. A well marked vagina 

 uterina (ovejector) is characteristic of all thelastomatids 

 and oxyurids but not of atractids. The Rhigon«matidae 

 are a group apart, in the Oxyuroidea, in female struc- 

 tures as in other characters. They are more like the 

 Ascaridoidea in that only the vagina vera takes part in 

 the formation of the heavily walled ovejector. In Rhigo- 

 nema infectum. (Fig. 119 D) the vagina vera is connected 

 with a massive sac and through this with the amphidel- 

 phic uteri. Artigas (1930) found this chamber absent 

 in other species and formed for them a new genus, 

 Dudekemia. In R. infectmn the ovarial end of each uterus 

 is set apart and serves as a spermatheca and fertilization 

 chamber; we therefore presume the larger chamber to 

 be an egg pouch. 



Fig. 122. FEMALE REPRODUCTIVE SYSTEM. 



A-H — Spiroiioura affine (A — Cross section near vulva; B — 

 B — Longitudinal section of vagina ; C — Surface section of vagina 

 showing muscles ; D — Surface view of uterus showing epithelium 

 and muscles ; E — Cross section of germinal region of ovary ; F — 

 CrosR section of vagina : G — Longitudinal section of blind end of 

 ovary; H — Surface view of epithelium in growth zone of ovary). 

 1 — Matraus inonhystera (Longitudinal reconstruction of vagina 

 vera). J-M and X — Hi/stri(inalhus rii/iilKS (J — Cross section of 

 vagina uterina ; K-L — Cross sections of vagina vera, K at valve ; 

 M — Uterus; X — Longitudinal reconstruction of vagina and uteri). 

 N-S — Oesophafiostomuni dentatmn (N-0 — Adjoining parts of ove- 

 jector, N is uterine while O shows connection of vagina vera to 

 other ovejector ; P — Distal part of ovejector ; R — Uterus near 

 ovejector; S — Uterus more distal). T-U — Ti-ichuris ovis {T — detail 

 of vaginal cuticle; U — Cross section near vulva). V — Trichiiris 

 suift (Ovary showing germinal region on one side). W — Dioctophyma 

 rvnnlf (Ovary showing germinal zone extending around surface). 

 Y-AA. — Cephalobellus papillifrfr (AA — Ovary in germinal zone; Y 

 and Z — Ovary in growth zone). BB-CC — Eiiterobias vennicHlaris 

 (Uterine musculature in living specimens, BB relaxed and CC 

 contracted). 



V, after Rauther, 191S, Zool. Jahrb. Abt. Morph. v. 40 ; W. 

 after Rauther, 19?.0. Handb. Zool. v. 2 ; Y-AA. after Chitwood & 

 Chitwood. 1933, Ztschr. Zellforsch. v. 19 (2). Remainder original. 



Within the Ascaridoidea no forms are Jcnown that 

 approach the simplicity of Tachygonetria vivipara; the 

 ovaries are always greatly elongated, commonly coiled. 

 Within the Cosmocereidae, Kathlaniidae* and Heterakidae, 

 most of the forms are primarily amphidelphic, with the 

 vulva usually more or less equatorial, while the Ascarid- 

 idae contain forms which are chiefly opisthodelphic, with 

 vulva shifted anteriad. The ovejector is seldom as promi- 

 nent an organ in this superfamily. In so far as informa- 

 tion is available the vagina of cosmocercids (Olsen, 1938) 

 and kathlaniids (Mackin, 1936) is entirely vagina vera, 

 i. e. the ectodermal part extends to the separation of 

 the two uteri. 



In Heterakis gallinae (Heterakidae) the heavily muscled 

 ovejector (Fig. 116 R) is vagina vera but in addition 

 there is an elongated vagina uterina which extends 

 posteriorly and is reflexed anteriad before connecting 

 with the amphidelphic uteri. For such a (relatively) 

 non-muscular modification of the vagina uterina we feel 

 that Seurat's term "trompe" or trunk may properly be 

 reserved. This same term would apply in the case of 

 Rhigonema (Fig. 119 D). Other heterakids including 

 Ascaridia lineata (Ackert, 1931), Allodapa numidica 

 (Seurat, 1915) and Maupasina weissi-\ (Seurat 1931) 

 have a short ovejector composed of vagina vera and a 

 long trunk composed of vagina uterina. The two former 

 species are amphidelphic while the latter is prodelphic 

 and like Rhigonema, possesses a large chamber at the end 

 of the ovejector, Seurat named this structure a bursa 

 copulatrix considering that it might function as a tem- 

 porary storage place for spermatozoa. Such a structure 

 also occurs in some spiruroids. 



Ascaridids are opisthodelphic as represented by Ascaris 

 lumbricoides (Fig. 117 L) ; the vulva is usually^ situated 

 preequatorially, the vagina directed posteriad, followed 

 l»y trunk and posteriorly directed parallel uteri. As in 

 heterakids, the vagina uterina (trunk) is not conspicu- 

 ously muscular and in many forms there is a dilation at 

 its clistal end which might serve equally well as a tem- 

 porary spermatheca (bursa copulatrix) or as a temporary 

 egg chamber. Polydelphy makes its appearance in the 

 genus so named, Folydelphis, in which there are four 

 parallel uteri arising at the end of the trunk while the 

 twin genus Hexametra is identical except that there are 

 six uteri. 



Camallanina. In this suborder the reproductive system 

 is chiefly amphidelphic, the vulva more or less equatorial. 

 Within the Uracunculoidea, the vagina is never heavily 

 muscled, nor are the uterine ovejectors developed. In 

 Philometra and Dracitnculus the vagina is functional 

 only in young females, becomirug rudimentary with 

 gravidity; in Micropleura it is retained but not especially 

 developed. The uteri of dracunculoids are great sacs 

 dilated with embryos and larvae filling practically the 

 entire body cavity. Camallanoids, on the contrary, re- 

 tain a functional muscular ovejector formed by the 

 vagina vera. In addition there may be a pair of short 

 uterine ovejectors in Cu-cuUanus (116 H) or an elongate 

 tubular trunk in Camallanus (Fig. 117 H). The family 

 Camallanidae is monodelphic, prodelphic but a postuterine 

 sac is generally present. The family Cucullanidae, while 

 developmentally amphidelphic, contains some transitions 

 toward prodelphy. 



Spiruriyia. In this suborder there is a well developed 

 muscular ovejector, the very heavily muscled part of 

 which is properly considered a vagina vera. Opisthodel- 

 phic, amphidelphic and prodelphic forms are all repre- 

 sented commonly within the group. Of these the opistho- 

 delphic forms are chiefly to be found in the Filarioidea, 

 Thelaziidae and Physalopteridae in all of which the 

 vulva is predominantly anterior in position. However, 

 even in these groups exceptional forms are amphidelphic 

 (Desmidocereella Filarioidea), prodelphic (Physocephalus, 

 Thelaziidae; Proleptus, Physalopteridae). The remaining 

 families, Spiruridae, Acuariidae and Gnathostomatidae 

 might be termed primarily amphidelphic or prodelphic 

 but there is too much variation except in the Gnathosto- 

 matidae for any generalization. The vagina vera seldom 

 if ever reaches the bifurcation of the uteri so that there 

 is always a trunk. This trunk has high epithelial cells 

 which extend to a variable degree beyond bifurcation of 



•The structure termed "'shell gland" by Mackin (1936) is the 

 oviduct. 



tThe uteri are parallel and directed anteriad, thereafter reflexed 

 posteriad, the ovaries being situated in the caudal region. Seurat 

 (1920) characterized this formation as opisthodelphic. 



149 



