F. A. Bather — Dinocystis Barroisi. 543 



IV. — Studies in Edrioasteroidea. I. Dinocystis Barroisi, 



N. G. ET SP., PSAMMITES DU CoNDBOZ. 



By F. A. Bather, M.A., F.G.S. 



(PLATE XXI.) 



Horizon and Locality. 



ON April 30th, 1897, the Trustees of the British Museum 

 purchased from Dr. F. Krantz, of Bonn, seven specimens 

 labelled " Agelacrinus, n.sp., Unter Devon, Condroz, Frankreich." 

 But the Condroz is a district in Belgium, south of Namur and 

 Liege, between the rivers Meuse and Ourthe ; the species do not 

 belong to Agelacrinus or any known genus ; and the matrix clearly 

 is that of the well-known " Psammites du Condroz," which are 

 Upper, not Lower, Devonian. The species, however, is new, and 

 would have been described by me many months ago had it not 

 been necessary to compare it with other species as rare as they 

 were obscure. The kindness of the authorities at the Imperial 

 University and at the Academy of Sciences in St. Petersburg, the 

 Museum of Practical Geology in London, and, most of all, at the 

 Geological Survey in Ottawa, has enabled me to make a fairly 

 satisfactory study of the forms that elucidate the Condroz species. 

 In addition to them, I have to thank my friend Professor Otto Jaekel, 

 who had at Berlin another specimen of this species, which be 

 purposed introducing to science in his forthcoming Phylogeny of 

 the Pelmatozoa under the name Dinocystis Barroisi ; on learning 

 that we had more and better specimens for study he generously 

 waived any objections he might have had to my prior publication. 



The ascription of these specimens to the "Psammites du 

 Condroz " is confirmed both by the Berlin specimen and by 

 a, statement in Dr. Michel Mourlon's " Geologic de la Belgique " 

 (tome ii, Bruxelles, 1881). A " Liste des fossiles des psammites 

 du Condroz " (p. 23) notes " Agelacrinus " as " tres-rare " in 

 " Assises de Montfort et d'Evieux," but refers to no published 

 authority for the statement. The " Assises " in question are 

 numbered III and IV by Mourlon, and are the lower two of his 

 divisions of the "psammites" (op. cit., tome i, pp. 92, 93). There 

 is little doubt but that the present species is the Agelacrinus of 

 Mourlon. 



The " Psammites du Condroz " consist of a micaceous sandstone 

 varying in coarseness, sometimes bluish but, in consequence of 

 weathering, usually brown or even reddish. The calcareous 

 constituents have been leached out, and the fossils occur as either 

 internal casts or external impressions. Unfortunately, the available 

 specimens of Dinocystis all belong to the former category. The 

 sandstone may be regarded either as an independent horizon above 

 the Famennian shales and below the Limestone of Etroeungt, or 

 as a littoral equivalent of the typical Famennian shales. The latter 

 view, that adopted by Eenevier, is supported by the fact that in 

 the Condroz area the Etroeungt Limestone is replaced by the shales 



