34 BRITISH FOSSIL SPONGES. 



chilleum, Aulocopium, Astrceospongia, Protospongia, and Acanthospongia ; and 

 references are given to the species described. Brachiospongia, Acestra, 

 Bothroconus, and some other genera are regarded as doubtful. 



186. 1881 Sollas, W. J. On Astroconia Granti, a new Lyssakine Hexactinellid 



from the Silurian Formation of Canada (Quart. Jbum. Geol. Soc, 

 vol. xxxvii, pp. 254—260, figs. 1—11). 

 Describes various forms of detached acerate and hexactinellid spicules, 

 which are referred to this new genus and species. 



187. 1881 Sollas, W. J. Note on the Occurrence of Sponge-Spicules in Chert 



from the Carboniferous Limestone of Ireland (Ann. and Mag. Nat. 

 Hist., vol. vii, pp. 141—143, fig. 1). 

 Mentions the occurrence, in some cases in great abundance, of spicules in 

 microscopic sections of chert, which had been described by Prof. Hull as of 

 inorganic origin. 



188. 1881 Whitfield, R. P. Observations on the Structure of Dictyophyton 



and its Affinities with certain Sponges (American Jbum. of Science, 



vol. xxii, pp. 53, 132). 

 The structure of this organism, which had been referred by Hall to Algae, 

 is compared to that of the recent JEuplectella, and it is supposed to have con- 

 sisted of siliceous fibres, although positive evidence for this is at present 

 wanting. 



In a subsequent note an example of JJphantcenia is described, in which the 

 spicules forming the longitudinal and transverse bundles are now preserved in 

 the condition of pyrite, and the rectangular spaces between the bundles are 

 also covered with a thin film of the same substance. 



189. 1880 Nicholson and Etheridge, Junr. A Monograph of the Silurian Fossils 



of the Girvan District. 

 A description is given of Ischadites Koenigii, Murch. ; its systematic posi- 

 tion is regarded as doubtful ; the siliceous rope of a Sponge is described under 

 the name of Hyalonema (?) Girvanense (p. 239, PL xix, figs. 1, 1 b). 



190. 1881 Whitfield, R. P. Remarks on Dictyophyton and descriptions of new 



species of allied forms from the Keokuk Beds at Crawfordsville, 



Indiana (Bulletin No. 1, American Mus. Nat. Hist., p. 10, Pis. 3, 4). 



Refers to the different names applied to this genus from time to time, and 



gives detailed descriptions of species of TJphantcenia and Dictyophyton. The 



structure is stated to consist of longitudinal and transverse fibres or threads, 



formed of bundles of cylindrical spicula. 



