Iiemispherical rustellum M ji In its aiitero-posterlor diameter and 

 tjO /* to 85 u in Its lateral diameter; base of rostellum armed witli 

 about 80-S5 hooklets measuring 6.5 /* to 7.5 ii. Suckers circu- 

 lar, small (25 /i to 35 /i), armed with a single row of hooklets 

 (6 11), with rather laige, bllobed base. Stroblla fomposeil of 

 2-5 .segments, first segment only aibout 56 /i long, the following 

 segments increasing in length and width. Genital pores iiiL- 

 gularly aHernate. situated at the anterior angle. The second 

 segment possesses well-developed male organs and the anlagen 

 of the female organs. In the third segment the testicles are 

 atrophied, the female organs (median posterior vitellarium, two 

 ovaries, rece.pt. sem., vagina) well develoied, but no uterus 

 present. In the fourth segment all the genital glands are 

 atrophied, and the segment is filled with numerous isolated 

 eggs (not in egg caipsules); ova 35 /* to 40 /^ ; hooks of oncosphere 

 10 ju to U /J. The segments have a great tendency to separate 

 more or less completely; the last segment, after separating, 

 remains in the intestine and grows to 2inni long by 1.25ni"> 

 broad (larger than the entire worm). 



Develapment: I>arval stage is found in slugs (Limax cinereus. 

 L. agrestis, and L. varlegatus, and develops from the oncos- 

 phere in less than twenty days; fed to chickens, the cysticer- 

 coid becomes adult with 4 segments at the end of eight days. 



Host: Chickens (Gallus domesticus). 



Geographical distribution: France (Rennes by Dujardln). in 

 le Nord by Davainc, in Lioiret by Lucet. in Indre-et-Lolre by 

 R. Blanchard, and Italy by G'rassl & Rovelli. 



Epidemics: Lucet observed a serious epizootic enteritis In 

 fowls produced by this parasite in Loiret (RaiUlet, 1893. p. 305). 



The life history of thi.s worm has been experimentally 

 demonstrated and this is one of the few tiii)eworms of 

 fduis wliicii can lie said to be i'(»iii|)araliv('ly well 

 kniiwii from a scientific stand|Hiiiit. 



20. DAVAINEA CIRCUMVALLATA (Krabbe, 1869) R. Blanchard. 1891. 



(isia. Taenia Unae Rud., pars; 1869, T. circumvallaui Krabh-; 

 1890, T. pluriuncinata Crety.) 



[PI. XVI, figs, 203-211.1 



Diagnosi.-^: Stroblla 40mm tn ]50mm long. He.-xd pyrifoim 

 0.627mm to O.Smm long by 0.598mm to 0.65mm broad. Rostellum 



