436 
Sclerostomes of the Horse 
peculiar in being bilobed, no trace of a median (dorsal) lobe being present 
(Text-fig. 7). The margins of the lateral lobes are finely denticulated 
as in the genus Triodontophorus. The ventral rays are slender and 
parallel, and of equal size. The medio-lateral ray is a little shorter 
than the other lateral rays and the postero-lateral is peculiar in posses¬ 
sing a short thick branch arising from near its base and projecting 
dorsally (Plate XXII, fig. 5, A.P.I.); this extra lateral ray terminates 
very bluntly, its exact shape and length vary considerably 1 . There is 
no median dorsal ray, the dorsal rays arising in two groups of four 
(Text-fig. 7 and Plate XXII, fig. 5). The externo-dorsal is the longest, 
the three other dorsals being sub-equal, the middle one is, however, a 
little shorter than the others. 
Fig. 7. Dorsal view of bursa of Oesophagodontus robustus Giles. d. dorsal rays. 
g.c. genital cone. 
The genital cone (Plate XXII, fig. 6 and Text-fig. 7) is short and 
broad, its shape being almost hemispherical; it bears a pair of small 
lateral papillae, whilst a conical lip-like process is situated medianly, 
just ventral to the cloacal opening. 
As in Triodontophorus and Cylichnostomum the dermal collar (Plate 
XXTI, figs. 5 and 6) is well developed, it occupies the ventral aspect 
of the genital cone only. The prebursal papillae are short. 
1 A very similar appendix to the postero-lateral ray is met with in Choniangium 
epistomum Piana and Stazzi (=Asifia vasifa Lane), a sclerostome parasite of the Indian 
elephant. Lane (1914) evidently overlooked Giles’ species when he wrote “any multi¬ 
plication of the lateral rays of a bursate nematode appears to be hitherto unknown, and 
the presence of this feature in the form just described to be unique.” Cf. also Railliet, 
Henry et Bauche (1914). 
