ANKYLOSTOMA DUODENALE 327 



Gen. 10. Ankylostoma, Dubini, 1843. 

 Syn. : Dochmius, Duj., 1845. 



Characterised by the dorsally directed abrupt truncation of the anterior 

 extremity within which is the large oral capsule ; the oral aperture is round 

 and contains two recurved chitinous teeth^at each side of the median line 

 on the ventral border, but only one_ dorsal tooth. In the base of the 

 oral capsule there are two chitinous supports on the ventral side and one 

 tooth on the dorsal side. The bursa is three-lobed, and is broader than 

 it is long ; there are two spicules ; the vulva is behind the middle ofj the 

 body. 1 



ij^j[Ankylostoma duodenale, Dubini, 1843. 



Syn. : Strongylus quadridentatus , v. Sieb., 1851 ; Dochmius anchylostomum , 

 Molin, 1860 ; Sclerostoma duodenale, Cobb., 1864; Str. duodenalis, Schneid. , 

 1866 ; Dochmius duodenalis, Lckt., 1876. 



The body is cylindrical ; attenuated anteriorly, and of a light 

 reddish colour. In the oral cavity on the ventral surface close 

 behind the orifice (fig. 214) there are four hook-like teeth directed 

 backwards ; on the dorsal surface there are two teeth directed 

 forwards ; in the base of the oral cavity there is one tooth 

 directed forward on the dorsal surface and two chitinous lamellae 

 spreading out leaf like on the ventral surface. The males measure 

 8 10 mm. in length, 0*4 0*5 mm. in breadth ; the bursa has two 

 large lateral and one small dorsal alar processes ; the rib of the 

 latter terminates into two tridentate points ; a curved rib directed 

 backwards arises from each side of the trunk of the central rib ; 

 each lateral wing is supported by four ribs ; the two spicules are 

 long and slender. The females measure 12 18 mm. in length, 

 the caudal extremity has a small spine ; the vulva is somewhat 

 in front of the posterior quarter of the body. The eggs are 

 elliptical and have thin shells, they measure 0-055 0*065 mm - m 

 length and 0*032 0*045 in breadth, and are laid in a state of 

 segmentation. 



Ankylostoma duodenale lives in the duodenum, more rarely in 

 the first part of the jejunum ; it is parasitical in human beings 

 and in a few anthropomorphous apes ; it appears to be distributed 

 over all the peopled parts of the earth; it is very common 

 in the warmer regions, and occurs also in the colder temperate 

 zones ; it is certainly not absent from Germany. 



1 Looss, A., " Ueb. d. Giltigk. d. Gattungsnamens Ancylostomum Dub." (C. f. B., 

 P. u. I. (i), Orig., 1902, xxxi., p. 422). 



