350 House-Flies in Mesopotamia 



faeces of the rabbit, after shaking up with saline and centrifuging 

 showed no cestode ova or any other sign of infection. 



Equally negative results attended the attempt to infect a frog (Rana 

 esculent a). 



7. LlTEEATURE AND CONCLUSION. 



In the literature of the Cestodes I have been able to find mentioned 

 but two species for which the house-fly is claimed as the intermediate 

 host. Both of these occur in chickens; they are: (1) Choanotaenia in- 

 fundibuliformis (Goeze 1782) Raillet 1896, and (2) Davainea cesticillus. 



With regard to Choanotaenia the account of the development of 

 this species is contained in a much quoted paper of Grassi and Rovelli(4) 

 in which they write, after remarking upon the wide distribution of this 

 species, which they call Taenia infundibuliformis — "La ragione si e che 

 1' oste intermedio e la Mosca (Musca domeslica). Noi abbiamo nella sua 

 cavita addominale trovati varie volta da 2 a 30-35 cisticercoidi, il cui 

 scolice e identico a quello della T. infundibuliformis.* Nello stesso la- 

 boratorio della Universita di Catania, dove tenevamo molto materiale 

 di Tenie dei Polli per i nostri esperimenti, abbiamo potuto accertarci che 

 alcune Mosche si erano infettate." 



They give one small figure of the cysticercoid which bears a rough 

 general resemblance to that in my figure 3, but neither the envelope 

 nor the vesicle V is shown, and the rostellum appears to be very small 

 or in a very completely retracted condition. 



In another paper (3) in which this species is mentioned Grassi and 

 Rovelli merely state that the intermediate host is the fly and that the 

 cysticercoid lacks a "tail," such as occurs in Dipylidium caninum, and 

 which is perhaps represented in my species by the vesicle V, in Figs. 1 b 

 and 1 c. 



Stiles (6) gives a detailed account of the adult of Choanotaenia in- 

 fundibuliformis under the name of Drepanidotaenia infundibuliformis 

 (Goeze 1782), together with a long list of synonyms. On p. 45 he states: 

 "Were it not for the fact that the original host (chickens) is known, 

 I have the most serious doubt whether it would ever be possible to 

 recognise this form ; and whether even the numerous specimens recorded 

 from chickens as T. infundibuliformis are to be considered as such is, 

 in my opinion an open question." On the same page he also states: 

 "as for the supposed life-history, with the fly as intermediate host, 

 although I am not willing to deny the correctness of the hypothesis, 

 I do insist that it is only an hypothesis...." 



