THE FOSSIL CRINOID GENUS VASOCRINUS LYON 



By Edwin Kirk 



Of the United States Geological Survey 



The present paper is not in the nature of another revision of the 

 genus Vasocnnus Lyon, but rather the purpose is to reestablish the 

 genus on the foundations originally laid by its author. In doing 

 this, to be sure, it will be necessary to revise Lyon's somewhat crude 

 and incorrect descriptions in important details. Through the kind- 

 ness of the late Dr. Frank Springer, in whose collection in the 

 United States National Museum Lyon's original types now are, I 

 liave had opportunity to study all of Lyon's material, together with 

 other specimens referable to the genus. As first examined Lyon's 

 types were found with the cup plates outlined in ink, presumably for 

 the guidance of the draftsman. As marked the plates conformed to 

 Lyon's descriptions, A casual inspection of the specimens, however, 

 showed that as regards the plates of the posterior interradius Lijon 

 had erred in his interpretation of the cup structure. The same mate- 

 rial is here refigured and the true structures shoAvn and described. 

 In addition information has been obtained in regard to the structure 

 of the tegmen. It is now found that Vasocnnus as based on Lyon's 

 own species is a quite different crinoid from what has generally been 

 supposed. 



In considering the status of the genus Vasoct^nus all references 

 subsequent to 1879 may be ignored. In their " Revision " ^ (pp. 

 94-96 (319-321)) Wachsmuth and Springer chose Cyathocrinus ly&ni 

 Hall, which is a synonym of Cyathocrinus Jiexadactylus Lyon and 

 Casseda}^, as type of the genus. They say (p, 95) : " In reconstructing 

 the genus we prefer to make Vasocrinus Lyoni {Gyatliocriwiis Lyoni 

 Hall), from Crawfordsville, the type, because it is found more per- 

 fectly preserved in the arm portion; but we scarcely doubt, to judge 

 from the brachials, as far as they are preserved, that the arms in the 

 Devonian species were constructed in a like manner." This generic 

 conception of Vasocrinus as modified by Wachsmuth and Springer has 



* Wachsmuth, Charles, and Springer, Frank, Revision of the Palacocrlnoidea, Part 1, 

 Acad. Nat. Sci. Philadelphia Proc. for 1879, pp. 226-378 (author's separate pp. 1-153), 

 pis. 1.5-17. 



No. 2760.-PROCEEDINGS U. S. NATIONAL MUSEUM, VOL. 74, ART, 15. 



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