. Annual report of the Regents. New York State Museum; Science. 430 Eefoet of the State Geologist. Hi triangular, elongate or sword shaped. They are formed of a strong chitinous frame and base, by the extremities of which the mandible is articulated to the cup. The space between the frame is occupied by a membrane, nearly always with a foramen, above which the occlusor muscles are inserted. These are usually two in number. The form of the retentive mandible is usually semi- circular or spatulate. They are generally simple, but sometimes bifid or trifid. They are without the continuous chitinou
. Annual report of the Regents. New York State Museum; Science. 430 Eefoet of the State Geologist. Hi triangular, elongate or sword shaped. They are formed of a strong chitinous frame and base, by the extremities of which the mandible is articulated to the cup. The space between the frame is occupied by a membrane, nearly always with a foramen, above which the occlusor muscles are inserted. These are usually two in number. The form of the retentive mandible is usually semi- circular or spatulate. They are generally simple, but sometimes bifid or trifid. They are without the continuous chitinous frames of the prehensile mandibles, and consist of a membrane sup- ported only by the base, or by a frame at the sides extending only a short distance from the base; the^foramen is generally absent, and the occlusor muscles are much weaker than in the other variety. The purpose of the avicularia is not known. By some it is thought that they procure food, and it is a favorite mode of illustration to picture an avicu-. FiG. 8. Menipea flagellifera. a, Sessile avicularia; v, Vibracula; p. Peristome; o, Opercula. Fig, 9. Bugula bicornis, showing two kinds of pedunculate avicularia, the larger one with the dlgitiform process (after Busk).. 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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Keywords: ., bookauthorne, bookcentury1800, bookdecade1880, booksubjectscience
