p. 5

costals plates six, large, forming more than half the height of the body, two of these are pentagonal, two are hexagonal, and the other two heptagonal; scapular plates six, alternating with the costal plates; interscapular plates two, resting on the truncated upper sides of the heptagonal costal plates; the upper edges of the scapular and inter scapular plates are interrupted and made irregular upon their upper margins by the arms, the lower joints of which rest on their indented edges. The summit presents the appearance of a depressed arch or dome, composed of numerous plates resting partly up on the upper [the upper] edges of the scapulars and partly upon the base of the arms, having on one side a mouth composed of six small triangular plates forming a little conical elevation; arms thirteen (the number sometimes variable), composed, from near the base upwards, of a double series