512 M. K. A. Zittel on Fossil Hexactinellida. 



surface coated with a smooth, finely porous siliceous mem- 

 brane, in which there are rather large roundish or oval aper- 

 tures belonging to the intercanal system. Skeleton consisting 

 of coalescent lantern-spicules. 



Manon megastoma^ E,om. Kr. 1. 9. 



Coeloptycldum confluens^ Fisch. v. Waldh. Bull. Soc. Imp. 

 Mosc. 1843, vol. xvi. pi. xvi. 1. 



Etheeidgia, E. Tate. 



Quart. Journ. Geol. Soc. 1865, vol. xxi. 43. 



Hemispherical ; on the plane lower surface radial tubes 

 issue from the centre ; and these are either united by broad 

 transverse bridges, or lie close together. These tubes send 

 upwards tortuous and anastomosing tubes, which form the 

 hemispherical upper surface. The latter is coated with a 

 smooth, finely porous siliceous membrane ; in its vertex there 

 is a deep depression ; other apertures of irregular form, like- 

 wise belonging to the intercanal system, are distributed over 

 the upper surface quite irregularly. The skeleton of the thin- 

 walled tubes consists of lantern-spicules. 



Coeloptychium verrucosum, Fisch. v. Waldh. Bull. Soc. 



Imp. Nat. Mosc. 1843, vol. xvi. pi. xvi. 

 C. Goldfussi, Fisch. ibid. 1844, vol. xvii. pi. vii. 2, 3. 

 '\Etheridgia mirabilis, R. Tate, I. c. pi. v. 1. 



TOULMINIA, Zitt. 



Sponge-body cup-shaped, very thick-walled, with a deep 

 central cavity. Root branched. Wall consisting of thin, 

 mgeandrically-twisted laminae. Upper margin truncated, 

 broad, coated with a smooth, finely porous siliceous mem- 

 brane. 



fCephalttes catenifer^ Toulmin Smith, Ann. & Mag. Nat. 



Hist. 1848, pi, xiv. f. 14-16. 

 to. compressusj T. Smith, ibido xiv. 10. 



Camerospongia, D'Orb. 



1847, Corn's ^lem. de Paleont. ii. p. 212. 



Sponge-body globular, hemispherical, or pyriform. Upper 

 half coated with a smooth, dense or finely porous siliceous 

 membrane, with a circular funnel-shaped depression in the 

 middle. Lower half of the sponge-body with tortuous ribs on 

 the outside. The sponge-body itself consists of thin-walled, 

 mseandrically contorted tubes, which are composed of several 



