THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE VI. VOL. I. 



No. v.— MAY, 1914. 



CD:RTG-TlSr J^JL. ..^K,TICLES. 



I. — Studies in Eduioastekoidea. Y. Steganoblastus} 



By F. A. Bather, M.A., D.Sc, F.R.S. 



Published by permission of the Trustees of the British Museum. 



(PLATE XV.) 



Peevio0s History. 



THIS form was first made known in 1897, by the late J. F. 

 Whiteaves, in a paper entitled "Description of a new genus 

 and species of Cystideaus from the Trenton Limestone at Ottawa" 

 (Canad. Hoc. Sci., vol. vii, No. 5, pp. 287-92). This part bears on 

 the wrapper the date " January, 1897 ", which is obviouslj' erroneous, 

 since the author dated his own contribution "April 28th, 1897", 

 and copies of it were first received in London on July 31 of that year. 



In that paper the species received the name Astrocystites ottawaen&is, 

 and was regarded as "most nearly related to Aster oblastus, Eichwald, 

 and . . . probably referable to the same family". In a letter sent 

 to Dr. Whiteaves by the next mail, I pointed out difficulties in this 

 interpretation of the structure, as well as difficulties in the name 

 Astrocystites. " You can," I wrote, "hardly have been aware that 

 Haeckel, in 1896, separated Asteroblastus tuberculatus of Schmidt 

 from A. stellatus under the new generic name of Asterocystis." 

 1 furtlier pointed out that the termination -ites was frequenth* 

 dropped, and was no real distinction ; also that aaTyp and not uaTpov 

 was the correct word to use in composition for the sense intended by 

 Dr. Whiteaves. A change of name therefore not only would avoid 

 confusion but seemed to me justified. Dr. Whiteaves accepted my 

 view, and in a "Postscript" (tom. cit., p. 395, January 7, 1898) 

 published the name which I suggested to him — " Steganohlastus, from 

 are^/auof, closely covered, with reference to the large covering plates 

 and covered mouth." In this Postscript he inadvertently alluded to 

 the species as Steganoblastus canade7isis instead of S. ottaicaensis. 



In consequence of my renuirks on the structure, Dr. Whiteaves 

 kindly lent me the two specimens belonging to the Geological Survey 

 of Canada, which, with an imperfect specimen lent me by Mr. Walter 

 K. Billings, made up all the known material. The first results of 

 my examination were summarized in Lankester's Treatise on Zoology, 

 vol. iii, pp. 209-10, text-fig. vii (1900), where I founded for the 

 reception of this genus the Family Steganoblastidse of the Class 

 Edrioasteroidea. 



^ Study IV appeared in the Geol. Mag. for March and April, 1914. 

 decade VI. — VOL. I. — XO. V. 13 



