646 TOKUYASU KUDO 
M. mandibuli-marginalis Blundschli (M. menti accessorius 
Kelchi) (fig. 6) 
This muscle is found in Europeans only as an infrequent vari- 
ation (Kelechi, Wood, Henle, Testut, Ruge, Seydel, Blundschli). 
Ruge has observed the muscle as a variety arising from the 
platysma, while Seydel considers it the remnant of a sphincter 
colli superficialis. 
I have encountered the muscle twice in the Japanese (in J VIII 
and J XII) in fifteen half faces. Thus it appears to be no rarity 
in the Japanese. In the latter (fig. 6) many isolated fibers ex- 
tend from the prolongation of the triangularis toward the ear. 
They lie superficially on the cheek portion of the platysma and 
cross that muscle. In the former two separate muscle strands 
radiate from the margin of the jaw bone upward in the form of 
a weak bow, concave on the anterior face. In a Chinese head 
Birkner has seen similar compact muscle strands directed toward 
the ear. 
M. triangularis (figs. 1 to 7) 
In Mongolians this muscle is mostly fan-shaped behind, below, 
and in front. As far as can be judged in my material, it is better 
developed in the Chinese than in Europeans. Likewise Birkner 
found this muscle well developed in three Chinese heads; the 
same is the case in the negro (Flower and Murie, Hamy, Hart- 
mann, Chudzinski, Popowsky, Eggeling and Loth) and in the 
Hottentots (Fetzer). 
In the Japanese and Chinese (figs. 3 and 7) the triangularis is 
commonly associated with the risorius; in Europeans, on the 
other hand, the muscle is usually isolated (four out of five heads). 
I have seen the well-known variations of the insertion ends of 
the fibers (Hisler), namely, the transition of bundles into the M. 
caninus, in five Japanese, one Chinese and three European heads; 
the transition into M. zygomaticus in one Chinese and seven 
Japanese; the transition into M. orbicularis oris sup. in nine 
Japanese, two Chinese, and two European heads. I have never 
met with a tendinous interruption of the muscle at the angle of 
