THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FIFTH SERIES.] 



No. 87. MARCH 1885. 



XV. — Description of a new Species of Crinoids with Articu- 

 lating Spines. By George Jennings Hinde, Ph.D., 

 F.G.S. 



[Plate VI.] 



In the ' Proceedings of the American Philosophical Society ' 

 for 1883 Prof. Henry S. Williams described a crinoid with 

 movable spines under the generic and specific term of Arthro- 

 acantha ithacensis. The forms described were merely im- 

 pressions of the organism in fine sandy shales, the objects 

 themselves having been dissolved away ; but, according to 

 Prof. Williams, the impressions were so perfect that the 

 minutest structural details could be readily ascertained. Not- 

 withstanding this circumstance, some little doubt was felt 

 whether these spines might not have been of a similar character 

 to those which in many other Palseocrinoids project from the 

 surface of their plates, and are but solid continuous extensions 

 of the plates themselves, and with them are immovably fixed 

 in the body-wall of the crinoid. The specimens in my pos- 

 session, however, which I now propose to describe, conclusively 

 show that Prof. Williams had correctly interpreted the im- 

 pressions and casts of the spines and plates in the Devonian 

 shales, and that, however novel the feature of movable spines 

 Ann. &Mag. N. Hist. Ser. 5. Vol. xv. 12 



