M. K. A. Zittel on Fossil Calcispongicc. 123 



4. Eudea globosa, Rom. ib. Taf. i. fig. 1. 



5. Monotheles punctata, Rom. ib. Taf. i. fig. 17. 



6. Monotheles stellata, From. In trod. pi. ii. fig. 6. 



7. Distheles depressa, From. Introd. pi. ii. fig. 7. 



8. Distheles irrflata, From. Cat. Rais. pi. ii. fig. 5. 



9. Distheles pedicidata, From. ib. pi. iii. fig. 1. 



10. Bcyphia foraminosa, Goldf. Taf. xxxi. fig. 4. 

 Endostoma foraminosum, Rom. Spongit. Taf. xiv. fig. 0. 



11. ScypMa tetragona, Goldf. tab. ii. fig. 2. 

 Endostoma tetrayonum, Rom. Spongit. Taf. xiv. fig. 7. 

 Polyendostoma socicde, Rom. ib. Taf. xiv. fig. 4. 



Myrmecium, Goldf. 



(Petr. Germ. p. 18.) 



{ bzemidium p. p., Goldf. 



Epiiheles p.p., From. 



Myrmecium, ? Gymnomyrmeciiim, Pom. 



Sponge small, hemispherical, spherical, or cylindrical, nar- 

 rowed below, shortly pedunculate, at the base with a smooth 

 or concentrically wrinkled dermal layer, which sometimes also 

 coats the whole of the sides. Vertex convex, with a round 

 osculum in the middle, serving as an opening to a narrow 

 tubular stomachal cavity, which traverses the whole sponge- 

 body vertically. There are also numerous small poriform 

 ostia distributed on the surface wherever it is not clothed with 

 the covering layer. 



In the central cavity terminate rather stout radial canals, 

 which follow a curved course from without and below, and 

 are furcate in the vicinity of the surface. Their ostia are 

 generally placed in longitudinal series in the wall of the 

 central tube. Other straight canals penetrate into the sponge- 

 body obliquely inwards and downwards from the superficial 

 ostia. 



The skeleton consists of a narrow-meshed tissue of rather 

 thin anastomosing fibres, usually composed of calcite, rarely 

 of silica. I have been unable to recognize spicules with 

 perfect certainty ; but certain parts of the calcite fibres appear 

 to me to contain three- or four-rayed stars. 



This genus is distinguished from Conjnella chiefly by the 

 fine skeletal fibres, the narrow central cavity, and the greatly 

 developed covering layer, which is always present and fre- 

 quently envelops the sponge-body up to the vertex. It is 

 fur the present not very sharply defined ; but the Upper-Ju- 

 rassic species belonging to it bear so peculiar a stamp that 

 I could not resolve to unite them with ( 'orynetta. 



