158 Dr. G. J. Hinde on a 



may be in the history of the Crinoidea, no doubt can be enter- 

 tained of the fact. 



My specimens, consisting of eleven more or less perfect 

 bodies and numerous fragments of stems, are from calcareous 

 shales of Middle Devonian age at Arkona, Province Ontario, 

 Canada. They were collected by myself between 1875 and 

 1878, and though fully conscious of the remarkable character 

 of the articulating spines which they possessed, other investi- 

 gations prevented me from describing them till now ; and it 

 is only since beginning to work at them quite recently that 

 I became aware that Prof. Williams had already described a 

 form with similar spines from a higher geological horizon in 

 the Devonian series at Ithaca, in the State of JS ew York. 



Though the specimens are somewhat crushed and distorted, 

 so that no single individual exhibits all the characters, yet 

 they possess the distinct advantage over those described by 

 Prof. Williams in that the objects themselves, and not merely 

 their casts, are present ; and by collating the different speci- 

 mens I have been enabled to ascertain that, while there can 

 be no doubt that they possess the same essential features as 

 the type of the genus, they yet vary sufficiently, in many 

 important features, to constitute a distinct species. The 

 characters shown in these specimens make it necessary to 

 extend and modify Prof. Williams's description of the genus 

 based on the casts of A. ithacensis. 



Before referring to these, however, I may state that the 

 name Arthracanthus was employed by Schmarda* in 1854 

 for a genus of Rotatoria. The term Arthroacantha, applied 

 by Williams to this genus of crinoids, is derived from the 

 same Greek words, and is essentially similar to Schmarda's, 

 though less correctly rendered. I consulted independently 

 two eminent scientific authorities who are specially familiar 

 with questions of nomenclature, and they agreed that the term 

 later employed was invalid, from its resemblance to that 

 previously used by Schmarda, and I propose therefore to sub- 

 stitute in its place the term Ilystricrinus^. As it will be 

 necessary to make reference to the new species described 

 below, 1 may here apply to it the name of Hystricrinus Car- 

 penteri, in honour of my friend Dr. P. Herbert Carpenter, 

 M.A. 



HysTKICRINUS— A rthroacantha, Williams, emend. 

 Generic characters. — Body of crinoid inversely conical or 



* I>enkschr. k. k. Akad. d. Wiss. Wien, yd vii. 1854, p. 22. 

 t "YuTfjit;, a porcupine. 



