46 MESOZOIC RADIATA. 



pistillum (Gold.) and Jerea pistilliformis (Lamx.), besides its pe- 

 culiar form, by the vertical tubes being confined to the central 

 part of the cylindrical mass, while in the terminal disc or trans- 

 verse section of those species they are seen to open almost uni- 

 formly through every part ; they are also much more numerous 

 and rather smaller than in the present fossil. 



Very common in the greensand of the Vale of Pewsey, Wilts. 



{Col. University of Cambridge.) 



Manon Reussii (M'Coy). 



Sp. Char. A large, auriform, foliaceous expansion, averaging 

 rather more than half an inch thick and from 3 to 5 inches in 

 diameter ; undulato-concave above and irregularly convex be- 

 low ; the pedicle of attachment small, excentric towards the 

 side where the margins are inrolled ; edge obtusely rounded, 

 of a fine lacunose or spongy texture ; upper and under surfaces 

 with thickly scattered, prominent, wart-like mouths of excre- 

 tory ducts a line in diameter, averaging twice their diameter 

 apart on the upper surface, more crowded and irregular on the 

 lower ; intervening spaces of a more dense and uniform porous 

 structure than the margins. 



Besides the diff'erence of form and size, this is distinguished 

 from the Spongia marginata (Phil., Geol. of Yorkshire) and M» 

 Phillipsii (Reuss, Versteinerungen der bohmischen Kreidefor- 

 mation) by having the large excretory pores on the outer as well 

 as on the upper surface ; the character is constant and strongly 

 marked. 



Common in the chalk of some parts of Yorkshire. 



{Col. University of Cambridge.) 



Manon foliaceum (M^Coy). 



Sp. Char. A large, flat, or slightly concave, thin foliaceous ex- 

 pansion (averaging 7 or 8 inches in diameter and quarter of an 

 inch thick) of a very dense, minutely porous structure ; margin 

 rounded ; upper surface with numerous very prominent ostiolse, 

 averaging twice their diameter apart, rather less than a line in 

 diameter, perpendicular to the surface near the base, but be- 

 coming obliquely elongated towards the margin like adpressed 

 tubuli ; under surface marked with concentric waves of growth 

 without ostiolse. 



This singularly thin expanded species has no resemblance to 

 any other I am acquainted with. 

 From the coralline oolite of Malton. 

 {Col. University of Cambridge.) 



