M. K. A. Zittel on Fossil Lithistidce. 389 



Family 2. Megamorina. 

 Megalithista, Zitt. 

 Eulespongia p. p., Quenst. 



Sponge pyriform, cylindrical, or cup-shaped, thick-walled, 

 with rather wide, tubular central cavity. Both surfaces with 

 round, irregularly scattered ostia of different sizes, from which 

 large canals penetrate the wall. Corpuscles very larg3, 

 smooth, curved, usually with two or three branches at each 

 end (PI. VIII. fig. 4), with shorter or longer axial canals. 

 They are irregularly interwoven. Small, simple, bacillar 

 spicules, and a few forked anchors also occur. The typical 

 species, from the Coral Rag of Nattheim, is 



1. Megalithista foraminosa^ Zitt, 



Irregularly cylindrical or elongate-ovate ; surface some- 

 times with a few broad longitudinal folds or tubercles. Ostia 

 of various sizes, the larger not uniformly distributed, but con- 

 centrated upon particular parts. Central cavity rather wide. 

 Upper margin rounded. 



Hitherto confounded with Cylindrophyma milleporataj 

 Goldf. Possibly one of the wo fragments described by 

 Quenstedt (Petr. cxx. 7) as Ailespongia^ from the White 

 Jura of the Oerlinger Thai, nf x Ulm, belongs to this genus. 



DOEYDEEMA, Zitt. 



Spongia, Phill. 

 Pohjjerea p. p., Rom. 

 Dichojerea p. p., Pom. 



Sponge simple or compound, cylindrical, pyriform, flat, or 

 composed of cylindrical, forked branches rounded at the ends. 

 Internally with several vertical tubes parallel to the longitu- 

 dinal axis. Surface with mesh-like openings \ to 1^ millim. 

 in diameter, formed by a reticulate arrangement of the skeletal 

 corpuscles. From these ostia simple radial canals penetrate 

 the sponge-body. Skeleton composed of very large, smooth 

 corpuscles of irregularly branched structure (PI. VIII. iig. 3) ; 

 their thick arms more or less curved, forked once or twice, 

 never running into root-like processes at the ends. Axial 

 canal short, simple, rarely divided into two or three short 

 branches. The corpuscles are loosely interlocked, and form a 

 coarse network at the surface. In well-preserved specimens 

 the meshes are filled with a dense tuft of long-shafted forked 

 anchors. The end of the shaft, which is directed inwards, 

 is pointed ; the opposite end thickened and furnished with 



