DESCRIPTION OF THOMAS'S ŒSOPHAGOSTOME, BY A. RAILLIET & A. HENRY.
To simplify the description of the Brazilian Œsophagostome, the study of which has been entrusted to us by Dr. H. Wolferstan Thomas, we shall first and foremost recall the general characters of the groups with which the worms of this genus are connected.
The genus Œsophagostomum belongs to the family of the Strongylidae, the sub-family of the Ankylostominæ, to the order of the Œsophagostomeæ.
The Strongylidæ are Meromyarian-nematodes (Schneider), secernentes (Linstow's) the oesophagus of which is more or less club-shaped, inflated. The males have two equal spicules and a caudal pouch provided with ribs. The females possess two ovaries.
The forms with buccal capsule constitute the sub-family of the Ankylostominæ.
The order of the Œsophagostomes has as its principal characters:—Caudal pouch with bifid frontal and middle ribs, the posterior and posterior external rising from a common trunk, the posterior bifurcated. Vulva at a short distance from the anus; uterus divergent. Ventral slit more or less evident.
Finally the genus (Molin) Œsophagostomum answers the following diagnosis:—Frontal extremity showing a slight cuticular projection (peristemic swelling), behind which there appears usually a second much fuller swelling (cephalic vesicle) which stops suddenly in the ventral region at the level of a transverse depression (ventral slit) existing even in the absence of the vesicle. Mouth opens into a buccal capsule of little height, furnished with a
