G15 



bark Id fnrm neck (108 fi broad); apex armed with retractile 

 hemispherical rostellum 55 // in its antero-posterior diameter and 

 tiO fi to 85 u in its lateral diameter; base of rostellum armed with 

 about 80-95 hooklets measuring- 6.5 [i to 7.5 fi. Suckers circu- 

 lar, small (25 n to 35 fi)^ armed with a single row of hooklets 

 (6 [i), with rather large, bilobed base. Strobila composed of 

 2-5 segments, first segm-3nt only about 56 fJ- long, the following 

 segments increasing in length and width. Genital pores irre- 

 gularly alternate, 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, recept. sem.. vagina) well develored, 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 ess caipsules); ova 35 /^ to 40 j«; hooks of oncosphere 

 10 /i to 11 //. The segments have a great tendency to separate 

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

 remains in the intestine and grows to 2mm long by 1.25mm 

 broad (larger than the entire worm). 



Develcipment: Larval stage is found in slug^s (Limax cinerous. 

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

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

 coid beco'mes adult with 4 segments at the end of eight days. 



Host: Chickens (Gallus domesticus). 



Geographical distribution: France (Rennes by Dujardin), in 

 le Nord by Davaine, in Loiret by Lucet, in Indre-et-Loire by 

 R. Blanchard, and Italy by G-rassi & Rovelli. 



Epidemics: Lucet observed a serious epizootic enteritis In 

 fowls produced hy this parasite in Loiret (Railliet. 1893, p. 305). 



The life hisloi y of tliis worm has been ex[)eriraentally 

 demonstrated and this is one of the few tapeworms of 

 fowls which can be said to be comparatively well 

 known from a scientific standpoint. 



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



(1S19, Taenia linae Rud., pars; 1869, T. circumvallata Kraltlx; 

 1890, T. pluriuncinata Crety.) 



[PI. XVI, figs, 203-211.] 



Diagnosis: Strobila 40mm to 150mm long. Head pyriform 

 0.627mm to O.Smiii long by 0.598mm to 0.65mm broad. RosteUum 



