﻿ON NEW AND OLD MIDDLE DEVONIC CRINOIDS 



Bv ELVIRA WOOD 



The Devonic crinoids in the collection of the United States 

 National Museum include a considerable number of unusually inter- 

 esting specimens. Of these, two genera and seven species are new, 

 while others show minor but noteworthy variations from forms 

 already described. 



These crinoids have been submitted to the writer for study through 

 the courtesy of Mr. Charles Schuchert, Assistant Curator. It gives 

 the writer pleasure, also, to acknowledge her indebtedness to Dr. 

 Charles D. Walcott, in whose laboratory a portion of the work was 

 done. 



The specimens in the collection of the Massachusetts Institute of 

 Technology were studied while the writer was connected with that 

 institution. 



The new forms, with one exception, are from the Traverse (Hamil- 

 ton) formation of Michigan, and belong mainly to the genera 

 Megistocrinus and Dolatocriiuts. A single specimen from the Onon- 

 daga of New York appears to be referable to no described genus. 



TRIPLETJROCRINUS n. gen. 

 Toi-, three; Trfcvpd, side; icpivov, lily. 



Dorsal cup including the patina only. Arms attached to a nearly 

 circular facet on the outer surface of the radials. Arms unbranched 

 and uniserial; composed of thick plates; ambulacral furrow deep; 

 axial canal large. Column obscurely triangular, with one central and 

 three smaller accessory canals. 



Genotype. — Tripleurocrinus Levis n. sp. 



This genus appears to be closely related to those of the family 

 Gasterocomidse so far as the parts preserved admit of comparison. 

 The structure of the anal area, if known, might show a different 

 relationship, but the genus may be referred provisionally to that 

 family. It differs from the genus Gasterocoma, of the Devonic of 

 ( rermanyj and from other genera of the Gasterocomidse in possessing 



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