508 M. K. A. Zittel on Fossil HexactinelUda. 



traverse the stem and the radial oflFshoots of the sponge-body. 

 Microstructure of the cup as in Ventriculites. The stem- and 

 root-branches consist of elongated siliceous fibres without axial 

 canals, which, by transverse unions, produce a hexactinelloid 

 latticework. 



^Scyphia cervicornis^ Goldf. iv. 11, xxv. 11. 



Sporadoscinia, Pomel (emend. Zitt.). 



Paleont. de I'Oran, p. 84. 



Cup-shaped or cylindrical, narrowed downwards, with a short, 

 simple or branched root. Both surfaces of the wall coated 

 with a coherent, sometimes porous, covering layer, in which 

 numerous axial crosses lie imbedded. Sunk into this covering 

 layer there are on the outside irregularly formed ostia of ctecal 

 radial canals ; on the inside the ostia stand in alternating rows 

 or in longitudinal fuiTOws. Root slightly developed, with 

 vertical tubes. Microstructm'e like that of the preceding 

 genus. 



Scyphia micrommata, Rom. Kr. ii. 11. 

 *6'. Decheni, Goldf. Ixv. 6. 



* Crihrospongia cariosa^ Rom. Spongit. ix. 7. 



LiCMOSiNiON, Pomel. 

 Paleont. de I'Oran, p. 89. 



Sponge-body laminiform, attached by a short stalk. Both 

 surfaces of the wall furnished with numerous, pretty large, 

 irregularly placed ostia of c^ecal canals. Skeleton consisting of 

 octahedrally perforated sexradiates, condensed at the surface 

 into a porous covering layer with axial canals. 



* Diplostoma folium J Rom. Spongit. ix. 6. 



POLTBLASTIDIUM, Zitt. 



Sponge-body polyzoic, with numerous buds standing round 

 an elongated axis. The buds are trochiforra, truncated at the 

 upper margin, with a rather narrow central cavity. Latticed 

 framework wide-meshed, with octahedrally perforated crossing- 

 nodes. The whole sm-face coated with a coherent, porous 

 covering layer, with numerous axial crosses. Radial canals 

 and ostia wanting. Numerous isolated rod-like spicules occur 

 in the interspaces of the skeleton. 



Polyhlastidiuni luxurianSj Zitt., n. sp. (Linden, near 

 Hanover.) 



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