Page:Smithsonian Miscellaneous Collections, Volume 85.djvu/108

Rh relatively smaller and more slender. Each limb has a strong proximal joint (coxopodite) to which the endopodite is attached; the latter is formed of four stout joints and two slender joints with two or three short spines at the end of the distal joints; the four joints between the proximal and slender sixth joint may have a flattened extension on the ventral side as in the endopodite of Marrella that gives them a greater transverse diameter, and this may also occur in the sixth joint; the distal joint is slender and probably cylindrical; the exopodite has not been seen attached to the protopodite, but from a number of specimens showing their position there is little doubt of their having been attached as on the thoracic limb of Marrella. The exopodite is an elongate oval, apparently unjointed lobe as seen in the specimen represented by figure 4, plate 17; a fringe of fine, short filaments occurs on the ventral and outer margins; the delicate structure and small size makes it difficult to determine its exact nature, but as far as known it recalls the exopodite of Neolenus. One specimen indicates that there may have been an anterior support for the exopodite that extended beyond the flat filamentous lobe and terminated in two minute spines; the proximal portion of the endopodites has been flaked off in this specimen so as to expose the exopodites; the slender distal extensions may belong to the exopodites or they may be the ends of the endopodites of the opposite side flexed under. I am inclined, however, to think that they belong with the exopodites. What may be a modified exopodite has been seen in one specimen; it projects from beside the posterior thoracic endopodite and consists of a central axis with seven sharp spines projecting from its posterior side and a terminal spine; or it may be an endopodite showing the edges of plate-like joints in the same manner as those of Marrella splendens (pl. 22, figs. 6, 7).

Digestive organs.—The mouth was situated at the ventral side and probably bounded in front by the labrum and on the sides by the mandibles; the mouth presumably opened into a gullet that passed into a large stomach apparently divided or forked anteriorly; from the rear of the stomach a straight intestine extended back to the anus. A strong, relatively large tube is given off from each side of the stomach at about the fifth segment; these have strong branches at the proximal end, one extending forward and another backward, both of which have short bifurcating branches on both the outer and inner sides. In nearly all well-preserved specimens the large tube and often the large connecting tubes are rounded as though they were distended when buried in the sediment; this would accord with the view that these were large digestive glands that contained food in process of