Habitat.—Found by Brumpt in tumours of the cæcum and colon of a native of the River Omo (Lake Rudolph), East Africa. Immature forms only were present. Adults have been found in similar tumours in monkeys.
Fig. 319.—Œsophagostomum stephanostomum var. thomasi. 1, male, natural size; 2, female, natural size; 3, head of female, ventral view, showing cephalic vesicle and ventral cleft limiting it behind, × 55; 4, head of female, dorsal view, × 225; 5, head of male, end view, showing external and internal leaf crowns, × 225; 6, tail of male, lateral view (cf. fig. 318, D), × 20; 7, tail of female, lateral view, × 20; 8, Œs. thomasi, posterior ray of bursa, × 150; 9, Œs. dentigerum, from chimpanzee, posterior ray of bursa, × 150; 10, Œs. stephanostomum, from gorilla, posterior ray of bursa, × 150.
Pathology.—They occur in hæmorrhagic cysts in the submucosa or muscularis mucosæ of the gut wall. The cysts project internally and externally, and contain immature adults, which eventually escape into the lumen of the gut.
Fig. 320.—Œsophagostomum stephanostomum var. thomasi: cæcum and ascending colon. Subperitoneal cysts are seen on the top right hand, and in the lumen of the gut numerous cysts arranged transversely. The small roundish patches are areas of necrosis in the cyst walls. (After Thomas.)
Œsophagostomum stephanostomum var. thomasi, Raill. and Henry, 1909.
Body thick, pointed only at the ends. Buccal capsule much reduced. External crown of thirty-eight leaflets (the “crown” nearest the centre of fig. 319, 5). Male 17 to 22 mm. long by 750 µ thick. Spicule 1·380 to 1·475 mm., slightly curved at the tip. Female, immature, 16 to 20 mm. long by 900 µ thick, tail ending in a little conical appendage. Anus 230 µ, vulva 500 µ to 525 µ from tip. Ovejectors close together. Uteri very short in form of oblong pouch.