167 



The parasite is usaally fouud below the narrowing of the large intestine, 

 where the latter changes from a sack-like receptacle to a large tube, 

 and below the mass of the tumors. The tumors may, however, extend 

 the entire length of the intestine. It is evident that the distribution of 

 the eggs of this adult would be favorable for sheep becoming again in-, 

 fected by them. 



The oral armature of the embryo from the tumors and the adult CEso- 

 phagostoma Golumbianum differ, that of the embryo appearing to be like a 

 chitinous cup comparable to that found in the young of the Sclerostoma 

 of sheep and the Dochmius of dogs. The young of these species, however, 

 differ as much from their adult form as the embryo in question does 

 from its supposed adult form. 



The anatomical point that the writer considers of the most moment is 

 that the embryosof the tumors possess a lapel-like fold on the ventral side 

 of the worm just anterior to the ventral cleft, the opening of the unicellu- 

 lar gland duct, and that the adult 0. Golumbianum, possesses a similar 

 fold identically situated. (See Plate XIV, Figs. 1, 2, and 3, and Plate 

 XXV, Figs. 2 and 3.) The absence of this feature in the embryos of 

 Sclerostoma and Dochmius that infest sheep at once precludes the possi- 

 bility that we have to deal with these species. That embryos of this 

 character and corresponding adults are found in the same sheep makes 

 the diagnosis more assured. Should we look for a host in some other 

 animal we should expect to find one that had all the opprtunities of 

 spreading the eggs that infect the sheep, but amongst our farm animals 

 we find no corresponding parasite, and other wild animals which miglit 

 be suspected as hosts are at the present time very rare. 



CESOPHAGOSTOMA COLUMBIANUM, n. sp. 



Description. — Male, 12 to 15"'™; female, 14 to 18""". Wonn similar in appearance 

 to Dochmius cernwus, but having its head bent into the form of a hook. Head ter- 

 minal, very short, somewhat thicker than the neck, and separated from it by a con- 

 striction. Papillae six, of which two are dorsal, two ventral, and two lateral. The 

 latter are more obtuse and are the openings of the lateral canals of the body. Mouth 

 terminal, supplied with a chitinous atmature, consisting of an annular ring, which 

 supports two systems of twenty-four teeth each; the outer circles are very long and 

 curved, so that near their base they form a truncated cone and at their free extremi- 

 ties an inverted truncated cone. Within the outer is situated the inner and shorter 

 row of bidentate teeth, so arranged that each tooth is opposite one in the outer row. 

 Beneath the armature is the tri-radiate opening of the oesophagus. Neck not inflated, 

 but provided with a lapel or fold of skin on the ventral side jnst in front of the 

 ventral cleft; the fold continues slightly on to the dorsal side. Two lateral, narrow, 

 membranous wings begin at this neck fold and continue for one-fourth the length of 

 the worm. The two lateral opposite papillas are in these wings, at the level of the 

 first third of the cesoph.agns. The pair of unicellular neck glands unite into a com- 

 mon duct and empty at the ventral cleft, situated beneath the nuchal fold. Male 

 about three-fourths the length of the female. Bursa saucer-shaped ; can be spread 

 symmetrically without tearing. Costte or ribs symmetrical; the ventral slightly 

 separated; the ventro-lateral forms with the lateral a group; the lateral also 

 slightly separated; the dorso-lateral forms with its fellow and the dorsal pair a 



