1. Three hundred and ninety-three strains of haemolytic streptococci from infective processes in animals were identified by means of Lancefield's precipitation test and their host association recorded. 2. 94.7 per cent. of haemolytic streptococci isolated from the horse were identified as group C, 72.2 per cent. of those from the cow belonged to group B, and 82 per cent. of strains from the dog proved to be group G. In both sheep and pigs the predominating group was group C, while the few strains obtained from cats all fell into group G. 3. These results, together with the findings recorded by previous workers, indicate the existence of a definite host -group relationship in these infections in animals as well as the recognised human-group A relationship. 4. The infrequency of generalised and suppurative streptococcal infections in cows, sheep, pigs and cats compared with the incidences observed in human beings, horses and dogs is commented upon. 5. The number of apparently normal dogs found to be carrying haemolytic streptococci in their throats was found to vary between thirty -four and sixty per cent.; the the public health aspect of this occurrence is noted. 6. The fibrinolysin production of one hundred and ninety-six of the above strains was investigated and it was determined that 42 per cent. of group C strains and. 14 per cent. of group G strains produced fibrinolysin. All members of groups B.E.F.K.L. & M were inactive, with the single exception of a group B strain. 7. The strains were tested against the fibrins of the horse, dog, cow, pig, sheep, and man, and of twenty - six active group C strains, twenty -three produced fibrinolysin, specific in action against horse's fibrin; two, a fibrinolysin specific against human fibrin, and one, a fibrinolysin specific against sheep's fibrin, while of thirteen active group C strains, nine were specific in action against human fibrin, three against horse's and human fibrin, and one against horse's fibrin alone. 8. The use of the fibrinolysin test. to detect potential human pathogens of group C as recommended by Sherman and Niven (1938) , and Hansen (1943) is confirmed and its adoption for the same purpose on strains of group C is advocated. 9. The test to determine the action of fibrnolysin on fibrinogen. is suggested as a more reliable means of detecting specific action of the enzyme than the use of preformed fibrin either from crude plasma or from fibrinogen thrombin mixtures. 10. The specificity of the fibrinolytic reaction is discussed, together with the production of autolysis and the possible relation of this reaction to the resistance of certain animal species to streptococcal infection. 11. Eighty -one strains of these streptococci were tested for evidence of the production of hyaluronidase by the method of Duran-Reynals. Ten per cent. were found to be active and included two group B strains and six group C strains. No members of group G were included amongst the active strains. 12. It is concluded from the results that fibrino-lysin and hyaluronidase, although produced by animal strains of haemolytic streptococci, are not important factors in the virulence of these organisms.