In the collection there is a minute toy drum of the same general shape, and the same form reappears in some of the whistles, in one of which (Fig. 247) the skin head and its fastenings are all carefully reproduced in miniature. The immediate original of this particular form of drum was probably made of wood. A drum, recently brought from Costa Rica was made by hollowing out a cylindrical piece of wood and stretching a piece of snakeskin across the top. The shape is nearly identical with that of these earthen specimens. _Wind instruments._--Earthenware wind instruments are found in considerable numbers and are associated with other relics in the tombs. Nearly all are very simple in construction and are limited in musical power, receiving and perhaps generally deserving no better name than whistles or toys. A few pieces are more pretentious and yield a number of notes, and if operated by skilled performers or properly concerted are capable of producing pleasing melodies. It is not difficult to determine the powers of individual instruments, but we cannot say to what extent these powers were understood by the original owners, nor can we say whether or not they were intended to be played in unison in such a way as to give a certain desired succession of intervals. There are, however, in a large number of these instruments a uniformity in construction and a certain close correspondence in the number and degree of the sounds that indicate the existence of well established standards. It does not appear absolutely certain to me that the system of intervals was made to conform to that of any known scale; but a difficulty arises in attempting to determine this point, as most of the pieces are more or less mutilated. We find also that the note producible by any given stop is not fixed in pitch, but varies, with the force of the breath, two or even three full intervals. As a result of this a glide is possible to the skilled performer from note to note and any desired pitch can be taken.