In order to establish a firmer classification of gobies, certain characters (listed in the title) were examined.The gobies studied were arranged in four groups on the basis of three featurs (Table2), namely, the presence or absence of the mesopterygoid and of the upper postcleithrum, and the number of branchiostegals.These characters were thought to be more reliable than the other four that were investigated-namely, the pelvic fins, scapula, lower postcleithrum, and suborbitals-because of individual variations in the latter at the intraspecific level and interspecific variations among related species.The characters of the four groups are shown in table2. Group 1 is thought to be the least specialized, because of minimal reduction of bones and the completely separated pelvic fins with a spine and five branched soft rays (except Percottus glehni).In many of the included species the enclosing scapula type, and in two of them a suborbital, were present. Groups 2 and 3 are intermediate between groups 1 and 4 from the point of view of these characters. Group 4 is regarded as the most specialized because of the greatest loss of bones.None of the members of this group (except one among threespecimens of Eleotriodes longipinnis and one among sixteen specimens of E.strigatus) displayed completely separated pelvic fins with five branched soft rays, and none had the enclosing scapula.Instead, the membrane uniting the pelvic fins, the pelvic frenum, fewer pelvic soft rays, and the blotched scapula or no scapula were found.Although group 4 seems capable of being divided, it is left undivided in this study because of the characters used. Owing to the limited number of species and characters examined here it is impossible to know more than that these four groups show four levels of specialization.