. Annual report of the Regents. New York State Museum; Science. Gexeea of the E'oeth American Palaeozoic Bryozoa. 451 In the Hippocrepian forms, one side of the lophophore, that on which the anus is situated, is prolonged in two triangular arms. The tentacles are arranged continuously on the outer and inner margins, making a Rouble row (fig. 23), in the form of a horseshoe, a fact from which the name Hippocrepian is given to this class of Bryozoa. This condition is not found in any marine form. The Hippocrepian forms have also another organ which is absent in those genera in which the lophopho
. Annual report of the Regents. New York State Museum; Science. Gexeea of the E'oeth American Palaeozoic Bryozoa. 451 In the Hippocrepian forms, one side of the lophophore, that on which the anus is situated, is prolonged in two triangular arms. The tentacles are arranged continuously on the outer and inner margins, making a Rouble row (fig. 23), in the form of a horseshoe, a fact from which the name Hippocrepian is given to this class of Bryozoa. This condition is not found in any marine form. The Hippocrepian forms have also another organ which is absent in those genera in which the lophophore forms a continu- ous circle. This is a hollow valve-like organ continuous with one side of the lophophore, and is known as the epistome. The in- terior communicates with the perigastric space by an opening in the lophophore (fig. 22, k). The walls which are turned toward the mouth are thick and are covered with a vibratile cilia; the others are membranous and Fig. 21. Membraniporapilosa. In one of the cells the animal Is partially retracted, in the other it is fully expanded (after Farre) . When the animal is protruded, this organ is in constant mo- tion, elevated and depressed. The elevation is effected by the action of a muscle (fig. 22, Z), to be hereafter described; while the depression is probably effected by the antagonistic elasticity of the organ itself, though it may be effected by the action of a muscle not yet observed. Notwithstanding this organ has been studied by many observ- ers, its purpose has not yet been 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 New York State Museum; University of the State of New York. Board of Regents. Albany : J. B. Lyon, State Printer
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