Abstract
The Gregarine described in the following account was first observed by one of us, in autumn, 1909, in the alimentary canal of fleas—
Ceratophyllus styx
Rothschild—from a sand-martin’s nest. We have since collected, from several localities in the Scottish Lowlands, numerous larval, pupal, and adult specimens of
C. styx
, in which we have observed the various phases of development of the parasite. We have also dissected about 500 fleas of other species, in order to determine whether they also harboured the Gregarine which we had found in
C. styx
. The species examined were
C. farreni
, Rothsch., from nests of the house-martin;
C.gallinæ
Schrank, from nests of the blue-tit,f the blackbird, the thrush, and the robin;
C. gallinulæ
, Dale, from nests of the chaffinch and blackbird;
Ctenoeephalus 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 and 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. R. Leuckart mentioned that he had observed Gregarines in the gut of flea-larvæ, but gave no other information regarding them. E. H. Ross 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 Ross 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, in the following terms: “
Actinocephalus parvus
, n. sp., im Darm der Larven von
Ceratophyllus fringillæ
(Wlk.) und
C. gallince
(Schrank). Das auf einem kurzen Halse des Protomerites sitzende, lange bestandige, scheibenformige Epimerit, trägt 8 Haken; Maximallänge der Sporonten 140
μ
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
fasciatus
, 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 cephaline Eugregarines, which have spores unarmed with spines.” He proposes to name the Gregarine
Agrippina bona
, and to refer it to a new family—the Agrippinidae. As this Gregarine exhibits features so striking as to require for its reception a new family, it is evidently different from that described below, for the latter is referable to a well-known genus, Steinina.
Agrippina bona
differs from the new species of described in the following pages, not only in certain points of structure, but in being restricted to the larval gut and fæces, for, in
S. rotundata
, the trophozoites, although occurring in the larva, reach their full size only in the adult flea.