38 



On a Greg arine present in Mid-Gut of Ceratophylli. 



pyriform. Adults solitary, except when association in pairs occurs preparatory 

 to the formation of gametes. Cysts spherical, 110 to 185 //. in diameter, 

 without sporoducts. Spores oval, 11 to 12 //. long, and about 7 fi broad. 



Habitat. — The mid-gut of certain species of bird-fleas of the genus 

 Ceratophyllus. 



DESCRIPTION OF PLATE. 



List of Reference Letters. 



A., anus ; Ep., epithelium of mid-gut ; G., gizzard ; Int., intestine ; K., karyosome ; 

 M., muscle-fibre ; M.G., mid-gut ; M.T., Malpighian tube; N., nucleus ; 03., cesophagus; 

 R., rectum ; R.P., rectal papilla. 



All the figures relate to Steinina rotundata, nov. sp., from the mid-gut of Ceratophyllus 

 styx, Rothsch. Figs. 1, 9, and 13 are from stained preparations ; the rest were drawn 

 from living specimens. 



Fig. 1. — Section of a portion of the epithelium of the mid-gut of a young larva, 3 mm. 

 long, to which a young trophozoite is attached. 



Fig. 2. — Two later trophic phases, from the mid-gut of a young adult flea. A exhibits the 

 division into epimerite, protomerite, and deutomerite ; B was lying free in 

 the cavity of the gut and was not differentiated into regions. 



Figs. 3, 4, 5, 6, 7. — Trophozoites from an adult flea. On dissection of the mid-gut 

 these specimens became free from the gut-wall. Note the varying form of the 

 epimerite, the vacuolation of the karyosome in figs. 4, 5, and the denser 

 chromatin-spherules in the karyosome of fig. 6. 



Fig. 8. — Almost full-grown adult (sporont or sporadin), found attached to the gut- 

 epithelium of an adult flea. Note the magnification is only half that of 

 figs. 3 to 7 and 9. 



Fig. 9. — Section of a portion of the wall of the mid-gut of an adult flea, in the epithelium 

 of which the epimerite of a well-grown trophozoite is deeply embedded. 



Fig. 10. — Outline of the gut — from the cesophagus to the anus — of an adult flea and of 

 its contained parasites. Only the proximal portions of the Malpighian tubes 

 are shown. The five cysts contained fully formed spores. The four tropho- 

 zoites were similar in form to that shown in fig. 2, B. 



Fig. 11. — Outline of the wall of a spore. 



Fig. 12. — A sporozoite, immediately after its liberation from the spore, drawn while 

 living. Note the slender, mobile "rostrum." The opposite end of the sporo- 

 zoite was bent into the form of a hook. 



Fig. 13. — Sporozoites, from a preparation fixed with osmic vapour and stained with 

 Leishman's stain. A, B, C, D, represent typical sporozoites ; those lettered 

 E, F, G, H are less usual forms. 



