Abstract
1) Morphological and ecological differences amongtwelve local races of spinous loaches from western Japan were described.
2) More than seventeen kinds of hybfids were produced among eleven local races collected from eight rivers and one lake.
3) When the local races were classified according to IKEDA's opinion, the males and females of all interspecific and intersubspecific hybrids were almost completely sterile. A simlar sterility was also found among some intrasubspecific hybrids.
4) From the standpoint of the physiological isolation, the Japanese spinous loaches may be divided into several species, differing from the classification by IKEDA.
