116 Dr. F. A. Bather — Studies in Edrioasteroidea. 



In brief, then, from the time of Billings down to the end of 

 last century, the genus Edrioaster remained most imperfectly, not 

 to say incorrectly, apprehended. Its importance was obvious, but 

 I did not dare to introduce it into any system of classification or any 

 theoretical discussion without having first-hand knowledge. The 

 opportunity for obtaining this was afforded by my friends Mr. Walter 

 E.. Billings, of Ottawa, and the late J. F. Whiteaves, of the Canadian 

 Geological Survey, who lent me excellent material, which I was 

 fortunately allowed to retain for several years. The need of time 

 as well as of material has never been more obvious. Before any 

 precise account could be written or any adequate figure drawn, it was 

 necessary to clean and develop the specimens with the utmost patience. 

 And here I have to acknowledge the great help rendered by my wife, 

 who devoted months of labour to a single specimen, thus enabling 

 Mr. G. C. Chubb to make the admirable drawings on Plate X. The 

 information thus obtained was utilized in the diagrams and brief 

 account of Edrioaster bigshyi published in A Treatise on Zoology, 

 vol. iii, Echinoderma, p. 209 (London, 1900), in the abstract of 

 a lecture "What is an Echinoderm ? " ' and in the Encyclopcedia 

 Britannica articles on " Echinodermata " (1902) and " Echinoderma" 

 (February, 1911). That specimen has been still further cleaned, 

 several other specimens have been prepared and studied, and the 

 results are given in the present paper. 



Since 1900 the only author to paj'' any particular attention to my 

 publications on Edrioasteroidea has been Mr. W. K. Spencer, who 

 criticized some of my conclusions in his interesting paper "On the 

 Structure and Affinities of Palceodiscus and Agelacrinus " (Proc. Roy. 

 Soc, vol. Ixxiv, pp. 31-46, pi. i, 1904), but who has since modified his 

 objections ("Brit. Palseoz. Asterozoa": Palaeont. Soc. vol. for 1913). 



Mateeial. 



The holotype of Edrioaster bigsbyi has never yet been fixed, and 

 should be chosen from among the original specimens described 

 and named by E. Billings (1857). On the generally admitted 

 assumption that these comprised the original of Billings' pi. viii, 

 fig. 1 (1858), I hereby select that specimen as holotype. This and the 

 other specimens described and figured by Billings in 1857 and 1858 

 are kept in the Victoria Memorial Museum at Ottawa. These 

 specimens are so imperfectly preserved that Mr. Whiteaves did not 

 consider it worth while to send them to me. He sent, liowever, the 

 following three specimens, the property of the same museum, and 

 belonging without any doubt to the same species. For convenience 

 of reference I have lettered them A-C. 



A. The original of Plate X. A theca in calcite in a matrix of very 

 hard, grey, shaly limestone, which, when the specimen was sent me, 

 covered the whole of its under face, but is now cleaned away. The 

 specimen is broken into three parts by a crack across the anterior ray 

 and another across the distal end of the right anterior ray. Part 

 of the theca comprising the distal end of the anterior ray is missing. 



^ Joum. London Coll. Sci. Soc, vol. viii, pp. 21-33, May, 1901. Also 

 Che cosa i un Echinoderma? Torino, October, 1901. 



