56 SILICEOUS SPONGES. 



of the sponge; in a large specimen it is 19 mm. wide at the summit. Specialized 

 canals do not appear to exist, and the circulation seems to have been carried on 

 through the interspaces of the spicular mesh. 



The spicules are relatively large, straight, or slightly bent, cylindrical, with nodose 

 extremities; they attain a length of 1-25 mm. In the interior of the sponge these 

 spicules are united into small fascicles, and interwoven at their extremities to form 

 an open meshwork. On the exterior surface, however, they are disposed without 

 any definite arrangement, and cross each other in every direction, forming a compact 

 surface-layer. 



This species is not uncommon in the Flamborough Chalk ; and may be distinguished 

 from the cylindrical forms of Pachinion and other genera occurring in the same beds 

 by the scattered layer of spicules on the exterior surface of the sponge, which have 

 been preserved, owing to their relatively large size. 



Distribution. Upper Chalk: Flamborough. Planer-Kalk: Dohrnten, near Salz- 

 gitter {ZitteVs coll.). 



Family AAVMOCLABMA, Zittel. 

 Genus CYLINDROPHYMA, Zittel, 1878. 



CyLINDROPHTMA MILLEPOBATA, Goldf. sp. 



1833. ScyjjJiia mtUeporata, Goldf. Petref. 1 Th. p. 8, t. 3. f. 2. 



1878. Scijphia milleporata, Queust. Petref. Bd. 5, p. 120, t. 121. f. 1-7. 



1878. Cylindrophyma milleporata, Zitt. Studien, II Ab. p. 70, t. 5. f. 6. 



Distribution. Upper Jura: Oerlingen; Wodna, Randen. 



Genus MELONELLA, Zittel, 1878. 

 Melonella radiata. Querist, sp. 



1858. Siphonia radiata, Quenst. Der Jura, p. 679, t. 82. f. 13. 

 1833. Siphonia pyriformis, p. p., Goldf. Petref. 1 Th. t. 35. f . 10. 

 1878. Siphonia radiata, Queust. Petref. Bd. 5, p. 249, t. 126. f. 60-72. 

 1878. Melonella radiata, Zitt. Studien, II Ab. p. 71, t. 5. f. 7. 



Distribution. Upper Jura : Heuberg. 



Genus LECANELLA, Zittel, 1878. 



LeCANELLA PATEKiEFOKMIS, Zittel. 



1878. Lecanella paterceformis, Zitt. Studien, II Ab. p. 71, t. 6. f. 1. 



Detached spicules of this species. 

 Distribution. Upper Chalk : Ahlten, Hanover. 



