S. Yokogawa 
165 
16. A group of cells just in front of the rectum and just over the posterior 
part of the genital primordiurn increases in number, invaginates, becomes 
differentiated into a tube which joins with the posterior part of the genital 
primordiurn. This tube differentiates into the vulva and vagina. Where it 
joins the posterior end of the internal reproductive organs there is an over¬ 
lapping so that the posterior end of the ovijector has a double origin. 
REFERENCES. 
Leuckart, R. (1887). Neue Beitrage zur Kenntniss des Baues und der Lebensgeschichte 
der Nematoden. Abhandl. d. math.-phys. Cl. d. k. sacks. Gesellsch. d. Wissensch. Leipzig. 
xiii. 565-704, 3 pis. 
Looss, A. (1897). Notizen zur Helminthologie Egyptens. 2. Centralbl.f. Baht. u. Parasitenk. 
(etc.), Jena, xxi. 913-26, 10 figs. 
(1905). The Anatomy and Life History of Agchylostoma dvodenale (Dub.). A Monograph. 
Part I. Records of the Egyptian Government School of Medicine, in. 1-158, 10 pis. 
- (1911). The Anatomy and Life History of Agchylostoma duodenale{ Dub.). A Monograph. 
Part II. Records of the Egyptian Government School of Medicine, iv. 167-611. 
Neuhaus, C. (1903). Die post-embryonale Entwickelung der Rhabditis nigrovenosa. Jenaische 
Ztschr. f. Naturw. Jena, xxxvii. 653-90, 2 pis. and 1 fig. in text. 
Theiler, H. and Robertson, W. (1915). Investigations into the Life History of the Wire- 
worm in Ostriches. 3rd and 4 th Reports of the Director of Veterinary Research, Depart¬ 
ment of Agriculture, Union of South Africa, pp. 293-336, 9 pis. 
Veglia, F. (1915). The Anatomy and Life History of the Haemonchus contortus (Rud.). 
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Union of South Africa, pp. 349-47, 22 pis. 
Yokogawa, S. (1920). A New Nematode from the Rat. Journ. Parasit. vn. 29-33, 2 pis. 
DESCRIPTION OF PLATES VII—XII. 
All figures were drawn with a camera lucida from living material. 
ABBREVIATIONS USED. 
agp, anterior part of genital primordiurn of male; be, buccal-cavity; bs, bursal space; eg, cervical 
gland cell; eg, cervical glands; cmg, cement gland; cs, cells which form spicules; dl, dorsal lobe 
of bursa; e, egg cell; ed, ejaculatory duct; eg, cells of esophageal glands; ep, excretory pore; 
ev, excretory vesicle; eso, beginning of external sex-organs; gp, genital primordiurn; iv, cells of 
intestinal valve; lb, lateral band; n, nerve ring; neg, nuclei of cervical gland; oej, opening of 
ejaculatory duct; oj, ovijector; ov, oviduct; ovs, sphincter of oviduct; pac, post-anal cell; ppa, 
pulvillus post-analis; poj, posterior division of ovijector; peo, posterior end of ovary; pdr, posterior 
degenerating region of genital primordiurn; pgp, posterior part of genital primordiurn of male; 
pwc, posterior wall of cloaca; r, rectum; re, cells of rectal ligament or sphincter; rm, rectal mem¬ 
brane; rms, retractor muscles of spicules; rs, space surrounding rectum; s, spicules; sr, seminal 
receptacle; sv, seminal vesicle; t, testis; u, uterus; v, vulva; vd, vas deferens; vg, vagina. 
PLATE VII. 
Fig. 1. Rhabditiform larva just after hatching, 15 hours after culturing in liquid medium. 
Fig. 2. Rhabditiform larva, partly developed, two days after culturing in liquid medium. 
Fig. 3. Full grown rhabditiform larva, just before first moult, with cells of the intestinal wall 
beginning to divide. 
Fig. 4. Larva preparing for the first moult, division and degeneration of outer layer of intestinal 
cells complete. 
