. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 454 NEW YORK STATE MUSEUM Springer's description. A medium-sized species, known only by the calyx. Base low, discoid, usually with remnant of indented scar of attach- ment at younger stage. Calyx with radials in position in form of an obscurely hexagonal, truncated pyramid, contracted at the top of the radials to less than half its diameter at the base. Radials narrowing upward to short distal faces. Anal plate long, narrow, projecting in an angular apex above the line of radials. Height of base ab
. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. 454 NEW YORK STATE MUSEUM Springer's description. A medium-sized species, known only by the calyx. Base low, discoid, usually with remnant of indented scar of attach- ment at younger stage. Calyx with radials in position in form of an obscurely hexagonal, truncated pyramid, contracted at the top of the radials to less than half its diameter at the base. Radials narrowing upward to short distal faces. Anal plate long, narrow, projecting in an angular apex above the line of radials. Height of base about one- tenth its width; height to width of calyx about I to , varying in eight specimens from. 6 to 15 mm high and 12 to 30 mm wide at the base; width of calyx at base two and a half times its diameter at the radial facets, where it ranges from 7 to 10 mm. Parts above radials not known. rigure 62 Edriocrinus dispansus. Ventral Horizon and locality. From, the Lower Helderberg, Sowingthe'suturelines Linden formation, Benton county, Tennessee. of the basak and the Types. Holotype in the U. S. National Museum, ridges marking the for- mer position of the number 27757. Other specimens in the collection of superimposed radials Doctor g ^ and anal plate. (After r ° Springer, 1920). Remarks. E . dispansus is introduced here for comparison with the other species of Edriocrinus. It is free in the adult stage. This form, as well as the .similar, smaller, attached form associated with it, described by Springer as E. adhaerans, repre- sents one extreme structurally of which E. pyriformis represents the other. In the specimen here figured the individual is attached to the shell of Leptaena rh ojm b o*i d a 1 e s , which it entirely covers and extends beyond. In his study of these forms Springer found that " the disk is usually marked by a shallow concavity or an indented scar of much less than its own width, in which a shell or other foreign object is sometimes still attache
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaleont, bookyear1923
