MALACOTYLEA. 



239 



anterior half of body only, and bears a styliform spine on the projecting apex. 



D. conjunction Cobb., lancet-shaped, 12 mm. long, in the liver of dog, rarely on 



man, East Indies. D. spathulat&n R. Leuck. 



= D. sinense Cobb., in liver of man and cat in 



Japan and China ; D. pidmonale Bb'lz, in the 



lungs of man in Japan and China. D. ophthal- 



mobiiim Dies., a doubtful species, 4 specimens 



only found, in the lens-capsule of a nine-months 



child. D. heterophyes in the intestine of man in 



Egypt. D. macrostommn Rud. (Fig. 191), in 



the intestine of insectivorous birds, with genital 



pore at hind end. The eggs are consumed by 



the snail, Succinea amphibia, in the gut of which 



the miracidium is set free ; this makes its way 



through the gut -wall into the tissues, and 



becomes a branched sporocyst, known as Leu- 



cochloridiuni paradoxum. Some of the branches 



extend into the tentacles, to which they give a 



peculiar appearance by their colouring of green 



and white bands and red tip. A bird, attracted 



by this, pecks off the tentacle, and so swallows 



a branch of the sporocyst, in which have been formed tailless Cercariae. The 



latter are thus transferred to the intestine of the final host. The remarkable 



feature about this life-history is that the Cercaria is never free, and is without a 



c 



FIG. 190. Distomum rathouisi 

 Poir., after Leuckart. 



Fio. 191. Life-history of Distomum macrostomum, after Heckert. a, Succinea amphibia contain- 

 ing a ripe sporocyst of a Leucochloridium in its right tentacle. &, Leucochloridimn paradoxum 

 isolated, c, Cercaria (tailless) ready for transference in a double membrane, d, sexual 

 Distomum macrostomum; D yolk-glands ; T testis ; Ov ovary ; LK canal of Laurer. The open- 

 ings of the vas defereiis and uterus are at the hind end. 



