EAPHIDONEMA. 199 



A small specimen measlires 28 mm. in width by 13 in height, whilst a large form is 

 55 by 42 mm. The walls are from 3-5 to 7 mm. in thickness. One surface of the 

 wall, generally the upper, has a compact dermal layer, perforated by circular aper- 

 tures, from 1 to 1*6 mm. in width, with well-defined slightly elevated margins. The 

 opposite surface is smooth ; the fibres are, in some instances at least, more slender 

 and closer arranged than those of the interior of the wall. 



The fibres, measured in a thin section, vary from "1 to 'So mm. in width; the 

 spicular structure is similar to that of B. contortum. 



This species appears to have been referred by Sharpe* to 3 f anon marginatum, 

 Phill. ; Daveyf has also placed it under the same designation, although he questions 

 the identity of Phillips's species from the Upper Chalk with the Farringdon speci- 

 mens. Mantell J has named it Tragos peziza, Goldf. 



Distribution. Lower Green Sand : Farringdon. 



Raphidonema macropoea, Sharpe, sp. (Plate XXXVII. fig. 4.) 



1854. Manon macropora, Sharpe, Quart. Journ. Geol. Soc. vol. x. p. 195, t. 5. f. 3, 4. 



1848. Chenendopora fimgiformis'^ , Mant. (non Lamx.), Wonders of Geolog)', p. 637. 



1874. Manon macropora, Davey, Traus. Newbury Field-Club, p. 15. 



1878. Catagma macropora, Sollas, Ann. & Mag. Nat. Hist. ser. 5, vol. ii. p. 356, f. 1. 



1878. Elasmostoma macropora, Zitt. Studien, III Ab. p. 44. 



1883. Elasmostoma acutimargo, Keeping (non Roem.), Fossils of Upware &c. p. 147. 



Sponges cup- or funnel-shaped, or forming convolute expansions. A small speci- 

 men measures 25 mm. in height by 23 in width, whilst a large example is 100 by 

 110 mm. The walls vary from 4 to 10 mm. in thickness. The inner or upper 

 surface of the wall is either even, or in some specimens is marked by concentric 

 rounded ridges and shallow furrows. It is furnished with a smooth, apparently 

 compact, dermal layer, which is perforated by circular or ovate apertures, from 1-5 

 to 3"5 mm. in width, disposed concentrically nearly in contact with each other. 

 Where the interior is ridged, the apertures occur in the intermediate furrows. Small 

 canals open immediately beneath these apertures. The outer surface of the wall is 

 uneven, sometimes with nodose excrescences ; only the naked fibres are shown. 



In a transverse microscopic section of a specimen from Upware, the fibres appear 

 as closely reticulating bands, from -13 to -26 mm. in width. The filiform, sinuous 

 spicules are more robust and less regularly disposed than in R. contortum. Though 

 apparently uniaxial, here and there forms can be detected which show the stunted ' 

 basal ray of three-rayed spicules, and it is probable that the majority of the spicules 

 are irregular three-rayed forms. 



* Quart. Journ. Geol. Soc. 1854, vol. s. p. 189. 



Trans. Newbury Field-Club, p. 15. 

 t Wonders of Geology, Gth ed. 1848, vol. ii. p. 636 ; Medals of Creation 1854, vol. i. p. 229. f. 1. 



