. Carnegie Institution of Washington publication. . FIG. 11.—Zygocardiac ossicles of: A, Carcinus; B, Hapalocarcinus. FIG. 12.—Urocardiac ossicle of Hapalocarcinus. X220. X220. I suppose that the plankton is separated from the respiratory current by movements of the nets of setae on the maxillipeds, resembling the sweeping action of the legs of Cirripedes. The smallest members of the plankton only, in view of the minute size of the apparatus, would be entrapped. They would then be sucked into the stomach by pulsating movements such as Mocquard has described in other Decapoda. He has shown that
. Carnegie Institution of Washington publication. . FIG. 11.—Zygocardiac ossicles of: A, Carcinus; B, Hapalocarcinus. FIG. 12.—Urocardiac ossicle of Hapalocarcinus. X220. X220. I suppose that the plankton is separated from the respiratory current by movements of the nets of setae on the maxillipeds, resembling the sweeping action of the legs of Cirripedes. The smallest members of the plankton only, in view of the minute size of the apparatus, would be entrapped. They would then be sucked into the stomach by pulsating movements such as Mocquard has described in other Decapoda. He has shown that the stomach functions in the manner of a pump by the alternate action of the dilator and constrictor muscles. By the expansion of the cardiac sac the partially chewed food is sucked into the stomach and on its constriction the fluid taken in is expelled, while the solids are retained, largely owing to the action of the subcesophageal valve. It will be observed that notwithstanding the simplification of structure in the stomach of Hapalocarcinus there is still left the combi-. 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 Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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