. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 166 DAVID DEAN AND PHYLLIS A. HATFIELD istic reticulate pattern of the pigment of the pharynx begins to develop at the 5-setiger stage (Fig. 2). The density of pigment increases with larval development until at the 14-setiger stage it appears as dense as that of the stomach-intestine. Posteriorly from the pharynx an unpigmented oesophagus, about one segment in length, leads to the densely pigmented stomach-intestine. The latter region has lateral segmental diverticula (Fig. 4). The most posterior portion of the gut. FI
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 166 DAVID DEAN AND PHYLLIS A. HATFIELD istic reticulate pattern of the pigment of the pharynx begins to develop at the 5-setiger stage (Fig. 2). The density of pigment increases with larval development until at the 14-setiger stage it appears as dense as that of the stomach-intestine. Posteriorly from the pharynx an unpigmented oesophagus, about one segment in length, leads to the densely pigmented stomach-intestine. The latter region has lateral segmental diverticula (Fig. 4). The most posterior portion of the gut. FIGURE 4. Fourteen-setiger stage in dorsal view. Nototrochs appear on setigers 1-11. Hooded crotchets appear in the neuropodia of the last three setigers. of young larvae is unpigmented (Fig. 1), while the gut in the region of the last few setigers of older larvae (Figs. 3, 4, 6) varies from partially to well pigmented. According to Hannerz (1956) the comparable region of N. tridentata is straight and unpigmented. In N. agilis, however, the gut is enlarged in the pygidial region and is pigmented (Figs. 3 and 4). In the present study the gut posterior to the last diverticula was ciliated. Ciliation of N. agilis larvae is difficult to observe, due to the dense pigment of the gut. Cilia are of more than one type. Those of the prototroch, telotroch and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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