ANCYLOSTOME^: 445 



Group. Ancylostomeae, Railliet and Henry, 1909. 



Bursa with anterior ray cleft, median double, 1 postero- and postero- 

 external arising from a common trunk, posterior bifurcate, each limb 

 being tridigitate. Vulva in posterior third of body. Uteri divergent. 



Contains the following genera : (i) Strongylus, 3 (2) Ancylostoma, 

 (3) Uncinaria, (4) Characostomum, etc. 



Genus. Ancylostoma, Dubini, 1843, emend. Looss, 1905. 



Ventral margin of mouth capsule armed with teeth, the "roots" 

 of which are continued backwards and appear on the external surface 

 of capsule as rib-like thickenings. Terminal third of dorsal ray 

 cleft. Genital tubes very long, with short, closely packed diagonal 

 convolutions. 



Ancylostoma duodenale, Dubini, 1843. 



Male 9 mm. long by 0-45 mm. thick, female 12 mm. long by 

 0*6 mm. thick. Pale flesh colour, or an intense red in posterior third. 

 Anteriorly may be more or less black due to (blood) pigment in the 

 cells of the chyle intestine (= stomach + small intestine). The worm 

 is about the same thickness all through and is plump and rigid. 

 Cuticle striated. The body has a marked torsion, so that if the ventral 

 side of the head is upwards the anus appears to open laterally and 

 vice versa. The dorsal curve of the head end is only slight and 

 the oesophagus is roughly cylindrical. 



Buccal Capsule. The buccal capsule is bent dorsally, 0*21 mm. 

 long, o'i9 mm. broad. If a worm is rolled under the cover-glass so 

 that the dorsal side is upwards, we observe the following features 

 (fig. 325) : In the dorsal edge of the chitinous capsule there is a gap 

 as if a U-piece had been punched out. This is the " dorsal gap or 

 incision." The so-called "dorsal teeth" are simply the rounded 

 edges of the tips of this gap. They project beyond the skin which 

 covers the capsule externally. Below this gap is seen a curved line 

 which, if followed along the sides of the capsule on each side, merges 

 into the base of the most posterior ventral tooth. This line is the 

 optical expression of a very shallow groove on the inside of the 

 capsule. The skin on the outside of the capsule, which is reflected 

 over the edge of and into the capsule, dips into this groove, which 

 gives it a firm attachment. Below the middle (dorsally) of this curved 

 line there is a thickening in the capsule wall, which is perforated by the 

 opening of the dorsal cesophageal gland. This is the "dorsal ridge" ; in 

 optical section it has a conical appearance with a lumen (of the duct). 



1 I.e., with a distinct space between the limbs. 



2 Strongylus (Syn. : Sclerostomum) differs slightly in its posterior ray from the other 

 genera of the group. Each bifurcation is trifurcate rather than tridigitate. 



