File:The American journal of science (1909) (18148985602).jpg

Title: The American journal of science
Identifier: americanjourna4271909newh (find matches)
Year: 1880 (1880s)
Authors:
Subjects: Science
Publisher: New Haven : J. D. & E. S. Dana
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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120 G. R. Wieland—On Marine Turtles. and forward ; for even in that portion of the outer border next to the humeral notch there are blunt spines. Did the spines of the marginals articulate with one or more carapacial and plastral rows of dermal ossifications, and thus afford the nearest approximation to the osteodermal mosaic of Dermochelys yet discovered by adding dermal ossification on all the keel lines, that is the neural keel, the pleural keel, the supra- marginal, and marginal
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keel! I Figure 10.—Archelonischyros x^. A large dermal ossicle found in connection with the plastron of the original type, but possibly dorsal. O, the outer view ; S, sectional view showing the extreme thinness of the element. Note that the asymmetry of this element and its dactylate border indicate not only connec- tion with other dermal elements, but the probability of the presence of entire series of such elements. believe such to be the case, for at least twTo elements referable to a similar additional series corresponding to the supra-pleural keel of Dermochelys have been recovered. Nor is it strange that more have not been obtained. A fine shark's tooth per- taining to a scavenger species related to Lam- na was found with the type, and clearly indi- cates that all dermal por- tions loosely affixed to other elements of the carapace or plastron must have been pecu- liarly liable to disassocia- tion. In what other than a supra-marginal or infra-marginal position is it possible to place the thin and distinctly asym- metrical element shown in figure 10 ? It represents an integral part either of the carapace or of the plastron. Further, the likewise unique element shown in connection with the marginal in figure 11 can not be interpreted as in other than a natural position. From the fact that it is digitate all around and slightly asymmetrical, it may be inferred that a series of such elements lay inside of, and articulated with, the superior borders of the marginals, alternating quite regularly with them in about a double number, and that beyond this space a second much thinner supra-marginal series was present. The space between the latter and the midline of the cara- pace, where, as has been already seen, the presence of a median row of supra-neural or in part osteodermal elements is demon- strated, may or may not have been continuously occupied by ossifications. In any event, there are the seven dorsal keels, as in Dermochelys. On the plastral side, direct evidence of

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