. Bulletin of the Department of Geology. Geology. Vol. 6] Merriam: Notes on Desmostylus. 409 segment of the tooth. A third upper cheek-tooth, M2, not yet in function, is seen in the jaw bone behind M1. In the lower jaw (figs. 5 to 7) there is less difference between the first and second cheek-teeth than in the upper series. The first two teeth, considered by Yoshiwara and Iwasaki as P3 and P4, each consist of seven pillars, but P., is much the smaller tooth, and is short-elliptical instead of long-quadrate in cross-section. M1. Figs. 4 to 7. Desmostylus, sp. Cheek-teeth in occlusal view, X %.
. Bulletin of the Department of Geology. Geology. Vol. 6] Merriam: Notes on Desmostylus. 409 segment of the tooth. A third upper cheek-tooth, M2, not yet in function, is seen in the jaw bone behind M1. In the lower jaw (figs. 5 to 7) there is less difference between the first and second cheek-teeth than in the upper series. The first two teeth, considered by Yoshiwara and Iwasaki as P3 and P4, each consist of seven pillars, but P., is much the smaller tooth, and is short-elliptical instead of long-quadrate in cross-section. M1. Figs. 4 to 7. Desmostylus, sp. Cheek-teeth in occlusal view, X %. Miocene of Japan. Fig. 4, M1 and PJ; fig. 5, Mt; fig. 6, P4; fig. 7, (After Yoshiwara and Iwasaki.) P4 consists of three transverse rows of pillars with two each in the anterior and middle segments, and three in the posterior one. P3 may be considered as having three transverse rows of two each with an isolated pillar at the anterior side of the tooth. The third lower cheek-tooth, M1? consists of only six pillars ar- ranged in three transverse pairs, but it is much larger than the second tooth, or P4. As the Japanese specimen evidently represents a young indi- vidual, it is not entirely certain how many cheek-teeth were present normally in the jaw of the adult Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original University of California, Berkeley. Dept. of Geology. Berkeley : The University Press
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