. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 501 made to communicate. This communication is rendered most efficient by the shape of the plates on the two sides, which are separated from one another so as to form a large ventral blood-space, &s, which is continuous the length of the gill. This space is continued dorsally between the plates of the two sides, and the spaces of the plates form lateral branches of it. Along each side of the ventral portion of each plate, lying just inside, and closely applied to the wall, is a chitinous rod, cr. These rods are much heavi
. Anatomischer Anzeiger. Anatomy, Comparative; Anatomy, Comparative. 501 made to communicate. This communication is rendered most efficient by the shape of the plates on the two sides, which are separated from one another so as to form a large ventral blood-space, &s, which is continuous the length of the gill. This space is continued dorsally between the plates of the two sides, and the spaces of the plates form lateral branches of it. Along each side of the ventral portion of each plate, lying just inside, and closely applied to the wall, is a chitinous rod, cr. These rods are much heavier near the median line, become thinner laterally, and taper away at their free ends. The chitinous rod of each side of each plate continues over to form the chitinous rod of the opposing side of the plate adjoining. That is, each chitinous rod is two- pronged, and helps to support two plates. Many of the muscle-fibers of the suspensory membrane, su, are continued along the inner sur- faces of the anterior walls of the plates. These were supposed by Mitsukuri (5) to be chitinous supports, but they were later shown by Kellogg (2) to be muscles. Many of the fibers apparently find insertion on the walls of the plates themselves, but not a few are inserted over the surfaces of the chitinous rods. Each gill has two rather large bundles of muscles running its entire length. The one above, ulm, is circular in cross-section and lies near the suspensory membrane. The one below, Urn, is somewhat crescent shaped in cross-section, and lies just below the large blood- space, bs. Each plate bears cilia along, and near, its ventral and part of its outer margin, but the cilia are not distributed over its general surface. Near the ends of the chitinous rods the cilia on the edges of the plates disappear, and those between the plates become modified, as described by Kellogg (2), for holding the plates together. The area covered by these cilia is rather limited, and above them the plates are not
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