266 



THE ANIMAL PARASITES OF MAN 



Dicroccelium dendriticum, Rud., 1819. 



Syn. : Dicroccelium lanceatum, Stil. and Hass., 1896 ; Fasciola lanceolata y 

 Rud., 1803 (nee Schrank, 1790) ; Distomum lanceolatum, Mehlis, 1825 ; Dicroccelium 

 lanceolatum, Dujardin, 1845. 



Body lancet-shaped, narrowing especially at the anterior extremity ; 

 length 8 to 10 mm., breadth 1-5 to 2-5 mm., the greatest breadth usually 

 behind the middle of the body. Suckers distant from each other by 

 about one-fifth the length of the body ; oral sucker about o- 5 mm., ventral 

 sucker about o'6 mm. Pharynx globular, adjoining the oral sucker; 

 oesophagus o'6 mm. in length ; intestinal caeca reach to four-fifths of 

 the body length. Genital pore at the level of the bifurcation of the 

 intestine ; cirrus pouch small and slender. The large, slightly lobed 

 testes lie obliquely one behind the other behind the ventral sucker ; 



FIG. 1 66. Eggs of Dicro- 

 ccelium dendriticum, Rud. 

 To the left seen flat, to right 

 lying on one side. 600/1. 



FIG. 167. Miracidia of 



Dicroccelium dendriticum. a, 



from the dorsum ; , from the 

 side. (After Leuckart.) 



the ovary, which is considerably smaller, is placed behind the pos- 

 terior one ; the vitellaria, commencing at the level of the posterior 

 testis, terminate far before the caeca. The uterus, situated behind the 

 ovary, extends throughout the posterior end, not confined to the central 

 field, but overlapping the lateral fields with its transverse coils ; at 

 the posterior edge of the body it turns back again and winds forwards 

 to the ovary in transverse loops, then between the testes, and finally, 

 dorsal to the ventral sucker, terminates in the genital pore. The 

 thick-shelled eggs when young are yellowish, when older dark brown. 

 They measure 38 /z, to 45 fj, by 22 //, to 30 //,. They contain an oval or 

 roundish miracidium, only the anterior part of which is ciliated, and 

 which possesses a rudimentary intestinal sac with a boring spine. 

 The miracidia do not hatch out in water spontaneously, but, accord- 

 ing to Leuckart, in the intestines of slugs (Limax, Arion), but they 

 do not develop either in these (slugs) or in water-snails. 



The lancet fluke inhabits the biliary duct of herbivorous and 

 omnivorous mammals (sheep, ox, goat, ass, horse, deer, hare, rabbit, 

 pig), and is often found associated with the liver fluke ; it is not, 

 however, so common nor so widely disseminated, nevertheless, it has 

 been met with outside of Europe, namely, in Algeria, Egypt, Siberia, 

 Turkestan, and North and South America. 



