BIBLIOGRAPHY. 5 



are believed to have bad powers of contraction and expansion, and the radiating 

 ridges of tbe under surface of the Sponge are stated to be fasciculi of muscular 

 fibres. 



14. 1816 Smith, W. Strata identified by Organised Fossils. 



Figures are given of species of Ventriculites and Cephalites from the Upper 

 Chalk under the name of flint Alcyonites. Specimens of Doryderma, Siphonia, 

 and Tremacystia from the Upper Greensand are similarly placed under Alcyo- 

 nites. These fossils are not described. 



15. 1820 Konig, C. Icones fossilium sectiles. 



Four species of hexactinellid Sponges from Jurassic strata are placed in the 

 genus Spongus, as Polypi, ordo incertus. The author remarks that these and 

 similar fossils are usually regarded as Alcyonia, but that true Alcyonia are 

 unknown in the fossil condition. 



1G. 1820 Schlotheim, B. F. v. Die Petrefaktenkunde. 



In this work fossil Sponges are not distinguished from Corals. Some 

 are named Fungiten and others Alcyonites, whilst under the term Spongiten 

 are included true Corals. 



17. 1820 Schweigger, A. F. Handbuch d. JSTaturges. d. skeletlosen ungegliederten 



Thiere. 

 Recent Sponges are regarded as Corals without polyps, and are placed under 

 three leading groups or genera, Achillea m, Marion or Tragos, and Scyphia. 

 These generic terms were subsequently very generally adopted for fossil 

 Sponges. 



18. 1821 Lamouroux, J. Exposition methodique des Genres de l'ordre des Poly- 



piers. 

 The fossil Sponges described and figured are classified in a peculiar manner. 

 The genus Eudea, a calcisponge, is placed in the order Millepora ; Hallirhoa, 

 a lithistid, in the order Alcyonia, whilst the nearly allied genus Jerea is placed 

 in the order Actinaires, together w T ith Ghenendopora, Hippalimus, and 

 Lymnorea. These bodies are stated to have been soft iu their living condi- 

 tion, and capable of expansion and contraction. 



19. 1822 Parkinson, J. An Introduction to the Study of Fossil Organic Remains. 



Fossil Sponges are definitely recognised as of the same nature as recent 

 forms, and their occurrence is noted in the Lower Greensand of Faringclon, 

 the Upper Greensand of Wiltshire, and in the flints of the Upper Chalk. They 

 are placed in the tribe Zoophytes. The genus Siphonia is defined, and its 

 principal character is stated to be "a spongeous substance, pierced by a bundle 



