. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 278 NEW YORK STATE MUSEUM These secundaxils either extend down to the radials or not — both conditions occurring in the same ray; pentagonal with their contiguous margins joining and their outer edges resting upon the interbrachial plates. One large interbrachial; hexagonal, reaching to the top of the first arm plate and incorporating it with the calyx. Tegmen. Structure unknown. Arms flat-backed, with a length of not more than 18 mm. First four or five proximal brachials wedge-shaped and arranged
. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 278 NEW YORK STATE MUSEUM These secundaxils either extend down to the radials or not — both conditions occurring in the same ray; pentagonal with their contiguous margins joining and their outer edges resting upon the interbrachial plates. One large interbrachial; hexagonal, reaching to the top of the first arm plate and incorporating it with the calyx. Tegmen. Structure unknown. Arms flat-backed, with a length of not more than 18 mm. First four or five proximal brachials wedge-shaped and arranged in a single series; above, arms biserial. Pinnules slender and of medium length; composed of long ossicles, thickened at the two ends and slightly constricted in the middle. First pin- nules found on the tertibrachs. Column, according to Hall, round (1858, p. 117), consisting of alternately thicker and thinner annulations in the small portion at that time attached to the specimen. Ornamentation. Radials marked by coarse radiating ridges which pass to the adjoining radials, basals, and Figure 50 Marsipo- . crinus tentacu- mterbrachials. 1 a t u s. Enlargement Horizon and locality. From the calcareous layers of of amis and pinnules. (After Hall, 1859). See the shaly limestone of the Lower Helderberg group (New plate 36. figure 18. g^^ Schoharie( N. y. Types. Holotype in the American Museum of Natural History, number 2303. Remarks. The specimen figured apparently had a portion of its stem attached at one time, and was so figured by Hall. This fragment is now missing. Hall (1858, p. 117) notes the occurrence of another speci- men apparently belonging to this species. It was enclosed in the solid stone and broken through the middle showing a long, slender anal tube. tentaculatus differs from the other species of Marsi- pocrinus in the comparatively large size of the primaxils, the smaller. Please note that these images are extracted from scanned page images that may have be
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaleont, bookyear1923
