Correspondence — Mr. F. A. Bather. VI. 136 



Mr. Mourlon most courteously sends me a drawing, here reproduced., 

 of the specimen mentioned by him as " Agelacrinus" in 1881. It is 

 not the "asterie" of Professor Malaise ; it is not a Protaster Decheni, 

 or any kin thereto ; but it is a fine specimen of an Edrioasteroid, 

 as large as, and more perfect than, the British Museum specimen 

 E 7581, with actinal and abactinal surfaces clearly shown ; and it 

 belongs incontestably to Dinocystis Barroisi. F. A. Bather. 



British Museum (Natural History). 

 February 5, 1899. 



II. Edrioasteb Buchianus Forbes sp. 



[Geol. Mag., n.s., Dec. IV, Vol. VII, pp. 193-204, Pis. VIII, IX, X ; 



May, 1900.] 



IN 1848, under the name Agelacrinites Buchianus, Edward Forbes 

 introduced to science " one of the most remarkable Cystideans 

 as yet discovered in British strata." His description and figures, 

 published in his memoir "On the CystideaB of the Silurian rocks 

 of the British Islands " (Mem. Geol. Surv. Gt. Brit., II, pt. ii ; see 

 pp. 519-523, and pi. xxiii), have not proved fully intelligible to 

 subsequent workers, even to those who have had the fossil before 

 them. Unfortunately J. W. Salter, in his " Appendix. On the Fossils 

 of North Wales," to " The Geology of North Wales " by A. C. Ramsay 

 (Mem. Geol. Surv. Gt. Brit., Ill, 1st ed., 1866), criticised a little, but 

 illuminated less ; while the same Appendix in the second edition, 

 1881, though "greatly enlarged and partly rearranged by Robert 

 Etheridge, F.R.S.," merely introduced verbal alterations into Salter's 

 account. 



Allusions to this fossil by writers who have not themselves 

 examined it serve chiefly to show the need that exists for a fresh 

 description. Through the kindness of the Director-General of the 

 Geological Survey and of Mr. E. T. Newton, to whom my sincere 

 thanks are here offered, the original specimens were placed at 

 my disposal for several months. About two years ago the first 

 draft of this paper and some of the illustrations were sent to 

 Dr. Otto Jaekel in Berlin, and have been utilised on pp. 44-46 

 of his splendid volume " Stammesgeschichte der Pelmatozoen. 

 I. Thecoidea und Cystoidea " (1899). Thanks to Mr. J. F. Whiteaves 

 and the Director of the Canadian Geological Survey, I subsequently 

 learned the true structure of Edrioaster Bigsbyi, which was unknown 

 to Dr. Jaekel when he wrote the pages referred to. Hence some 

 interpretations in the present account differ from those given 

 by Dr. Jaekel. They agree, however, with the statements in 

 chapter xii — The Edrioasteroidea — of " A Treatise on Zoology, 

 Part III, The Echinoderma," edited by Professor E. Ray Lankester 



