Correlated Abnormalities in the Scutes and Bony Plates of the Carapace of the Sculptured Tortoise

Parker, G

A typical carapace of the sculptured tortoise (Chelopus insculptus LeC.) is composed of fifty bony plates, so united as to form a strong dorsal shield, and of thirty-eight horny scutes covering this shield externally. These elements are arranged as shown in Fig. I, in which the black lines represent the limits of the bony plates, and the lighter ones those of the scutes. The scutes form three series : first, a median set, which, beginning at the anterior end and proceeding posteriorly, consists of a narrow nuchal scute, five large central scutes, and a pair of pygal scutes, one right and the other left; secondly, four pairs of large centro-lateral scutes, which flank the median series, except at the anterior and the posterior ends ; and, thirdly, eleven pairs of marginal scutes, which bound the periphery of the carapace, except where the nuchal and the pair of pygal scutes reach the edge. The bony plates (Fig. r, black outlines) are also arranged in three series. The median one is composed of twelve plates, which, beginning at the anterior end, are, first, a large nuchal plate; next, eight neural plates; and, finally, three pygal plates, one behind the other. Eight pairs of costal plates abut with their central ends on the median series, and extend laterally well towards the edge of the carapace. Excepting where the nuchal plate and last pygal plate reach the edge, the carapace is bounded by eleven pairs of marginal plates. Although the scutes and bony plates are arranged upon similar plans, the two sets of elements do not coincide either in numbers or in exact positions.

Correlated Abnormalities in the Scutes and Bony Plates of the Carapace of the Sculptured Tortoise

Series