TAXOCRINIDAE 



353 



GNORIMOCRINUS Wachsmuth and Springer 



Plate XLVII, figs. 1-17 



Gnorimocrinus Wachsmuth and Springer, Revision Palaeocrinoidea, pt. i, 1879, p. 50; Proc. Acad. Nat. 

 Sci. Philadelphia, 1890, p. 388. — Zittel-Eastman, Textbook Palaeontology, 1896, p. 163 (2d Ed., 

 1913, p. 205). — Bather, Rep. British Assoc, for 1898 [1899], p. 923; Treatise on Zoology (Lankester), 

 pt. 3, 1900, p. 189.— Springer, Jour. Geology, XIV, 1906, p. 515. 



Fig. 47. Gnorimocrinus 



Taxocrinidae with rays not abutting above interbrachial areas. Crown 

 rather low and rotund. Infrabasals low, usually exposed, forming small part 

 of calyx wall. Posterior basal elongate. Radianal rhombic, obliquely to lower 

 left of right posterior radial. Interbrachials few or usually wanting, and areas 

 filled with perisome. Primibrachs two. Arms dichotomous, divergent. Column 

 short, not enlarging next to calyx, terminating in a branched root. 



Genotype. Taxocrinus expansus Angelin. 



Distribution. Silurian; Gotland and the United States. 



Gnorimocrinus was proposed by Wachsmuth and Springer as a subgenus to receive all 

 of Angelin's Silurian Taxocrini, with the Devonian Zeacrinus excavatus of Schultze added. 

 From the diagnosis the chief character on which the separation from Taxocrinus was based 

 is clear, as shown by the following extract : " Figure irregular, lacking the bilateral sym- 

 metry of that genus. The basal on the posterior side is exceedingly large, reaching almost 

 to the top of the adjoining first radials. The first anal plate, instead of resting upon the 

 truncated upper side of that basal, leans against the oblique right side and the adjoining 

 first radial." That is to say, in present terminology, it has the radianal obliquely below the 

 right posterior radial. That this was the one thing relied upon is emphasized by the note in 

 the Revision of the Palaeocrinoidea, pt. 1, p. 50, under G. distensus: " In this species, as 

 also G. punctatus, the irregular arrangement of the anal area is not sufficiently shown in the 

 figures." My investigation of this group in 1906 led to the recognition of two kinds of 

 irregularity in the anal side worthy of generic distinction, viz. : ( 1 ) where the radianal is in 

 the form and position of a radial, under the right posterior ray ; and (2) where it has been 



