Belonging to this class are the two handles on pl. XXXIX, which are in the Museum in Rome. They have been illustrated in colors by Pigorini. Through the interest of Dr. Lothrop we are enabled to present photographs of these two very interesting objects, together with some additional observations concerning them. The first piece (pl. XXXIX, _a_, and fig. 19 after Pigorini), is in the form of a crouching figure with an animal head and wide-open mouth. It has been described as a knife handle, like the other specimen (_b_), which is unquestionably of that character, but Dr. Lothrop writes that the front of this piece (_a_), where the knife blade should be inserted, is smoothly covered with a kind of cement, while in the belly of the figure is a large hole. From Dr. Lothrop’s examination of the specimen he was unable to satisfy himself whether it was a knife handle or was intended to be placed on the head of a staff. The materials used for the incrustation are turquois, reddish shell, dull white shell, mother-of-pearl, and small flakes of gold. In the Pigorini illustration, which represents the side opposite that shown here, two flakes of gold are shown, one in the eye, the other on the arm between elbow and shoulder. The other piece (pl. XXXIX, _b_), unquestionably a knife handle, as stated, of the same technique as the specimens in the British Museum, represents a crouching human figure. The materials are turquois, dark-green malachite, white shell, mother-of-pearl, and red shell. Lothrop calls our attention to the tiny pieces of turquois set in shell on the shoulder and in other places. He also states that a portion of a broken chert (?) blade is still imbedded in the socket in front of the figure. _Human Femur Musical Instrument_ The last of the specimens of mosaic to be described is the musical instrument (_omichicauaztli_) made from a left human femur, illustrated on pl. XL. This unique example, which is in the Museum in Rome, has been reproduced in colors by Pigorini. The mosaic seems to have been confined to the head and neck, although the trochanter major may also have been covered at one time. The incrustation at present consists of gum in which are pinkish-orange bits of colored shell. A modern copper chain is attached to the bone, from which hangs an oliva shell, undoubtedly ancient. [Illustration: PL. XL HUMAN FEMUR MUSICAL INSTRUMENT WITH MOSAIC DECORATION PREHISTORIC AND ETHNOGRAPHIC MUSEUM, ROME] According to Dr. Lothrop, the oliva shell shows signs of wear, and was probably the instrument used for rasping the bone, as the bone is sound and produces a rather musical tone when scraped with the shell, as if the bone were of china.