BIBLIOGRAPHY. 11 



50. 1848 Roemer, Ferd. Ueber eine neue Art der Gattung BlumenbacMum, 



Koenig, und melire unzweifelhafte Spongien in Obersilurischen 

 Kalkscliichten der Grafschaft Decatur im Staate Illinois in Nord 

 America (Leonhard u. Brown's Neues Jahrbuch, pp. 680 — 686, PL IX). 

 Recognises the similarity in the nature of the spicules of Blumenbachium 

 meniscus (now Astrceospongia) to that of living siliceous Sponges. Undoubted 

 Sponges from the Silurian strata (Niagara group) of North America are 

 compared with Cretaceous Sponges and placed in the genus Svphonia. Sub- 

 sequently the author placed these forms in a distinct genus, Astylospongia. 



51. 1848 M'Cot, F. On some new Mesozoic Radiata (Ann. and Mag. Nat. Hist. 



2nd ser., vol. ii, p. 397). 

 Describes the superficial characters of four species of Cretaceous and 

 Oolitic Sponges. No figures are given. 



52. 1848 Mantell, G. A. "Wonders of Geology, 6th edition. 



In this edition various species of Sponges from the Chalk and Greensand 

 are figured, and referred to in general terms as Sponges and Zoophytes. 

 Ventriculites is still stated to have been contractile. 



53. 1848 Chaelesworth, B. On the Mineral Condition and General Affinities of 



the Zoophytes of the Chalk at Flamborough and Bridlington {Proc. 

 Yorlcs. Phil. Soc, vol. i, p. 73). 

 These Sponges are apparently regarded as having been originally of a 

 horny character, and attention is called to the fact that their tissues are now 

 silicified. The different species named by Phillips are believed to be merely 

 modifications of a single form, for which the author proposes the name 

 Bhizosjpongia polymorpha. 



54. 1849-52 D'Oebigny, A. Prodrome de Paleontologie. 



The Sponges are placed under Amorphozoa, numerous genera and species 

 are introduced, but the characters given are so brief and indefinite that, in 

 the absence of figures, it is impracticable to recognise them satisfactorily. 



55. 1850 King, W. Monograph of the Permian Fossils (Pal. Soc, pp. 11—14, 



PI. 2). 

 Refers some doubtful organisms to the genera Scyphia, Mammillopora, 

 Tragos, and Bothroconis, n. g. Only their external characters are described. 



56. 1850 Dixon, F. Geology and Fossils of Sussex. 



Some specimens and polished surfaces of Siphonia in flint are figured, 

 but nothing is stated of them beyond the fact that they are Sponges. 



