Page:Smithsonian Miscellaneous Collections, Volume 85.djvu/119

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no. 3
burgess shale fossils—walcott
29

Labrum.—The labrum is attached to the strong frontal rim (doublure) of the ventral side of the carapace (fig. 9), and extends back to within a short distance below the posterior median margin of the carapace; its posterior lateral angles are extended into short, spine-like projections and the posterior margin appears to have been provided with two short points. The labrum appears to have covered the

Fig. 9.—Marrella splendens Walcott.

Restoration as described in text: a, antennae; c.sp., carapace spine; d, doublure or reflex of anterior margin of carapace; e, eye; en, endopodite; ex, exopodite; m, mandible; m', maxillula; m'', maxilla; t, telson.

anterior portion of the mouth; this is indicated by the proximal end of the protopodite or basal joint of the large mandible and that of the antennae passing beneath it in many specimens (see pl. 22).

Eyes.—The eyes (fig. 9) have not been seen from the dorsal side of any of the several hundred specimens preserving the carapace, and rarely from the ventral side; this leads to the conclusions (a) that they were located on the lower anterior margin in such a position as to be concealed when the carapace was flattened by compression;