Researches on the rugae palatinae transversus were made by using plaster impression models of palates of 60 head of experimental beagles (male : 31, female : 29). Possible relationship between bones and rugae was also studied by their radiographic observations. Measured values of palates 1. The average width between the canines was 30.6 mm for male and 28.7 mm for female ; the average of the largest palatine width was 53.5 mm for male and 50.6 mm female ; the average width between the 1st molars was 30.5 mm for male and 29.1 mm for female ; that between the 2nd molars was 29.8 mm for male, and 28.6 mm for female. 2. The average palatine length (between median line and the line connecting the most inner projecting point of the 2nd molars) was 78.3 mm for male and 73.5 mm for female. 3. Sex difference existed in both of palatine width and length of the part anterior to the 4th premolar. That is, the anterior part of the female palate was narrower and compressed lengthwise, compared with that of male palate. Morphology of rugae palatinae 1. Forty heads of beagles (male : 17, female : 23) had 9 rugae, and 19 heads of beagles (male : 13, female : 6) 10 rugae. No sex difference was observed in the incidence of rugae. 2. No sex difference was observed in the appearing condition for the morphology of rugae. 3. Almost all the rugae were symmetrical and continuous. 4. For both sexes the 5th and 6th rugae were diversified morphologically. The other rugae had little variation. 5. The most posterior margin of rugae was around the medialis of the 2nd molar. Radiographic observation It is considered that there is no morphological relationship between rugae and bony palates, and yet rugae are formed with some functional significance, independent of bones.
