MORPHOLOGICAL-CHARACTERISTICS IN THE 2 FO RMS OF FLATFISH, GENUS PLEURONICHTHYS, IN KIISUIDO CHANNEL WATERS OFF THE PACIFIC COAST OF CENTRAL JAPAN

Morphological differences between the two forms of Pleuronicthys were investigated. These two forms, Honmeita and Bakemeita, were clearly di stinguished by comparing the arrangement of scales on the right side o f the body. Scales were arranged regularly in a line on the central pa rt of the right body side in the Honmeita, but were arranged irregular ly in the Bakemeita except near the lateral line. The mean numbers of precaudal vertebrae, dorsal fin rays, anal fin rays, caudal fin rays a nd upper gill rakers of nine meristic characters examined were differe nt at a statistically significant level between the two forms. The rel ative growth of various body parts to the body length, such as body he ight, diameter of eye, depth of caudal peduncle, length of caudal pedu ncle, height of longest dorsal say, length of longest pectral ray and length of longest anal ray were significantly different between the tw o forms. Branching of the lateral line under the base of the dorsal fi n was observed in 9.2 percent of Honmeita, and 84.4 percent of Bakemei ta. The complete differences in the arrangement of scales and the stat istical differences in these morphological characters provide evidence of the distinctiveness of the two forms as the species.