Abstract
The author investigated the incidence and morphology of the preauricular groove in 60 male and 40 female Japanese macerated pelves, and the following results were obtained: 1) In the innominate bone, the preauricular groove was found far more frequently in Japanese and Indians than in the Whites in both sexes. 2) The incidence of the groove on the innominate bone was 100% in females and 91.1% in males. So the presence or abse nce of the groove has no significance for the sex determination of the innominate bone in Japanese. 3) When the gr o oves were classified into " Cavity type " and " Furrow type " in regard to its general shape, it was found t hat the former was more frequent in females and the latter in males. For the sex determination of the innominate bone, it is therefore suggested that the shape of the groove rather than its presence or absence should be taken into consideration. 4) Occasionally a shallow depression was observed at the posterior portion of the arcuate line close to the anterior angle of the auricular surface. This was revealed to be nothing but the structure for the insertion of the anterior sacro-iliac ligament. It was a little more frequently found in males than in females. 5) In the sacrum, the groove was unexpectedly frequent. It was narrow and shallow and not so marked as that of the innominate bone. The presence or absence of the groove can be used as a supplementary factor for the sex determination of the sacrum, so far as the sex difference in the incidence is statistically significant.
