. Bulletins of American paleontology. North American Mitrate Stylophorans: Parsley spines, and differentiated marginal and somatic plates. Syzygial sutures have been observed in the styloids of Enoploura, and pillar structures, similar to those in sand dollars, have been observed on both sides of the distal thecal opening in Ateleocystites Billings, 1858 (Kolata and Jollie, 1982) and in Anomalocystites Hall, 1858 (herein). Evidence for a water-vascular system in the Stylophora is good. The best evidence is seen in the aulacophore of Phyllocystis Thoral, 1935 in the form of parallel grooves and
. Bulletins of American paleontology. North American Mitrate Stylophorans: Parsley spines, and differentiated marginal and somatic plates. Syzygial sutures have been observed in the styloids of Enoploura, and pillar structures, similar to those in sand dollars, have been observed on both sides of the distal thecal opening in Ateleocystites Billings, 1858 (Kolata and Jollie, 1982) and in Anomalocystites Hall, 1858 (herein). Evidence for a water-vascular system in the Stylophora is good. The best evidence is seen in the aulacophore of Phyllocystis Thoral, 1935 in the form of parallel grooves and transverse grooves con- necting to the main food groove (Ubaghs, 1968a, p. S529; Ubaghs, 1969, pp. 32-36). Similar structures, less well defined, are seen in the aulacophore of Mi- trocystites Barrande, 1887 (Ubaghs, 1968a, p. S531). In both cases shallow pits at the ends of the transverse grooves would have been sites of the ampullae for the podia. Structures such as cothumopores and ctenoid organs have been variously interpreted but are prob- ably respiratory. In toto, the combination of charac- teristic echinoderm features seems sufficient to place stylophorans in the Echinodermata. Morphology, Functional Morphology, and Life Habits Orientation The two major morphological parts of a stylophoran are the theca and the aulacophore (Text-fig. 1). The mitrate theca commonly has single or paired movable spines at the opposite end of the theca from the au- lacophore. The proximal ends of the theca and of the aulacophore are at their junction: it should be noted that the aulacophore is often inset several segments into the theca. The terms oral and aboral are not syn- onymous with proximal and distal, respectively, with regard to the theca, because the oral opening appears to be at the distal end of the proximal aulacophore. Thus, either on the theca or on the aulacophore, distal should be interpreted as away from where the theca and aulacophore join. In this sense it is similar to
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