1. Sanguinicola megalobramae sp. nov. Diagnosis: Body lanceolate with conspicuous marginal spines except for two extremi-ties, of which the anterior end may be protruded in form of a proboscis with 4--5 rows ofcrepe line. Length 1. 25--1. 74 (1. 54)mm, width 0.23--0. 42(0. 31)mm.Mouth subcircular,ventral, within which has rod-like organellae; buccal tube nerrow, followed by an enlargedpharynx, within which there are eight spindle-shaped glandular cells; oesophagus slenderand long 0. 341 mm, ending in the form of an irregular ball or pyriform shaped intestinalcaecum, 0. 037 mm in length, 0. 035 mm in width. Testes consisting of 18--22 pairs of va-sicles extending on both sides of mid-line, ventral to ovary where it curves toward theleft side and becomes thick-walled seminal vasicle; male genital pore slightly sinistral,opening in a conical papilla on dorsal body surface. Ovary butterfly-shaped, immediatlyposterior to testes, oviduct arising from posterior of ovary,turning sinistrally tomake a loop and then turning to the right, and widening into a spindle-shaped structure,in which containing numerous sperms, and then uniting with the vitelline duct to forman ovovitelline duct; ootype circular in form containing only one egg, uterus short, withsoveral eggs. Famale genital pore situated in front of male. Egg oval in shape, withoutany projection or spine 0. 066--0. 28(0. 178)mm in length nd 0. 018--0. 020(0 .019) mmin width. Miracidium possesed a dish-like eye located at the medium of body. Sporocystoval or ball-shaped, thin walled, consisting of 8 cercaria in various stages of development,parasitized in digestive gland of Gyraulus albus. Host: Megalobrama amblycephala. Intermediate host: Gyraulus albus. Habitat: Bulbus arteriosus. Locality: Hatchery of Wang-Tien lake and Institute of Hydrobiology, Wuchang,Hupei Province. Type specimen: Institute of Hydrobiology. 2. Sanguinicola sp. Diagnosis: Body spindle--shaped, a little smaller than S.megalobramae, length 1.0-1. 2 mm, width 0.2--0.4 mm. Both lateral margins of body armed with spines, whichhave three types, short rod-like on anterier region, long and broad lanceolate on middleand slender at base on posterior, 91--93 in total number. Mouth, buccal tube, pharynx andoesophagus like S. magalobramae, while intestinal intestinal caecum is quite different, beingX--shaped,usually four lobes in number, but sometimes with a small one in addition. Testeswith 22 pairs of opposite or alternate lobes, of which one or two pairs of the middie regionbeing smaller. Ovary round, situated behind testes, ootype cirular, 30.6 in diameteruterus usually with several eggs; vitelline gland ventro-leteral in position, rather few innumber, posterior to ovary; eggs smooth, long oval in dorsal view, triangular in lateral,48--52(43. 0 ) μ long, 15. 3-20. 4(18. 5) μ in. width. Host: Megalobrama amblycephala. Habitat: bulbus arteriosus. Sanguinicolosis of blunt-snout bream occurred in the fish pond of Hupi province,in 1965 and 1973. It always causes the death of small fingerliugs, about 3. 3--4. 5 cm insize. The agencies are two species of bllood fukes, Sanguinicola megalobramae sp. nov. andSanguinicola sp. The morphlogy, ecology and development of the egg, miracidium, oercariae, andadults of agent are observed and described in detail. It is found that the intermediate hostof this blood fluke is a snail--Gyraulus albus Muller. Expriments on artificial infectionof the cercariae to the fish is larvae had been made. The period of egg-laying of this blood fluke is from July to May of the next year.Most of the adults live in the bulbus arteriosus of the heart, and the eggs distribute withthe flowing of the blood current, mainly to gills and kidney. If large number of eggs crowding in the lamellae of the gill, the young fish would besuffocated to death. If large number of cereariae occur in the pond, the infected fish lar-vae would become abnormal or dying. Eliminating tte intermediate host--G. albus, and killing the carcariae in fish pondare proposed for tbe treatment of this disease.