32 



Drs. J. H. Ashworth and T. Rettie. 



[Sept. 28, 



C. gallinulce, Dale, from nests of the chaffinch and blackbird ; Ctenocephalus 

 canis, Curtis, from rabbits ; and Pulex irritans, Linn., from a dog-kennel.. 

 All the series of C. styx dissected proved to be heavily infected, the 

 percentage carrying Gregarines ranging from 65 to 100. The degree of 

 infection was much less in the case of C. farreni and G. gallince — about 

 7 per cent, in the former and 5 per cent, in the latter — while the remaining 

 species above mentioned were found to be free from Gregarines. 



There are four previous records of the occurrence of Gregarines in fleas. 

 E. Leuckart* mentioned that he had observed Gregarines in the gut of 

 flea-larvae, but gave no other information regarding them. E. H. Kossf found 

 specimens, for which he proposed the name Gregarina ctenocephali canis, 

 in the alimentary canal of adult examples of the dog-flea — " Ctenocephalus 

 serraticeps," collected in Egypt. He described the trophozoites, which were 

 frequently found in pairs, as rostrated and pear-shaped, and gave a brief 

 account of the life-history of the parasite, at least, of those phases which 

 occur in the adult flea. The description given is, however, not sufficient to 

 permit the organism to be identified with certainty, but several of the 

 features mentioned by Eoss indicate that the " Gregarina " which he observed 

 is distinct from the organism which forms the subject of the present 

 communication. The third record is by Wellmer,t in the following terms : 

 " Actinocephalus parvus, n. sp., im Darm der Larven von Ceratophyllus 

 fringillm (Wlk.) und C. gallince (Schrank). Das auf einem kurzen Halse 

 des Protomerites sitzende, lange bestandige, scheibenformige Epimerit, 

 tragt 8 Haken ; Maximallange der Sporonten 140 p." This Gregarine is 

 markedly different from ours in the nature of the armature of the epimerite 

 and in other respects. The fourth record, by C. Strickland,§ relates to a 

 Gregarine which lives for part of its life in the alimentary tract of the larva 

 of Ceratophyllus fasciatns, and " for the other part lives freely in the 

 excrement of this host." Strickland states that " the form of its epimerite 

 and spores|| precludes us from placing it in any of the known families of 



from a hole in a wall. This nest, in regard to protection and supply of moisture, was 

 comparable to those of the sand-martin, and, like the latter, was evidently favourable to 

 the survival of the spores of the Gregarine and to the chances of infection of the flea- 

 larvse. 



* 'Arch. f. Naturgesch.,' 26 Jahrg., 1861, Bd. 2, p. 263. 

 t 'Ann. Trop. Med.,' Liverpool, 1909, vol. 2, pp. 359-363. 



\ 'Zool. Anz.,' 1910, Bd. 35, p. 533. Wellmer has since figured a cephalont and a 

 sporont of Actinocephalus parvus in his Inaug. Diss., ' Sporozoen Ostpreussischer Arthro- 

 poden,' Konigsberg, 1911, p. 33. This memoir is also published in 'Schr. Physik.-okonom. 

 Ges.,' Konigsberg, Jahrg. 52, 1911, Heft 2. 



§ ' Camb. Phil. Soc. Proc.,' 1912, vol. 16, pp. 460, 461. 



|| No details of the forms of these are given. 



