M. K. A. Zittel on Fossil Lithistidce. 479 



lower half, or nearly the whole surface, with an apparently 

 smooth covering layer as thick as thin paper. The parts not 

 covered with this layer rough, sometimes traversed by radia- 

 ting furrows issuing from one or more shallow depressions ; at 

 the vertex tubular vertical canals open into these furrows. 

 Skeletal corpuscles rather large, smooth, quadriradiate, united 

 by short, thick, root-like ramihcations, forming thickened 

 nodes, in which the ends of four arms usually unite. Cor- 

 puscles with a fine axial cross. The covering layer consists 

 of small, flat, indistinctly triradiate corpuscles, covered with 

 processes, and very closely packed together, and of forked 

 anchors, the three prongs of which are long, widely forked 

 and spread in a plane, so as usually to lie quite on the sur- 

 face. Large bacillar spicules are scattered upon the parts not 

 covered by this layer. All the species are from the Upper 

 Cretaceous. 



1. Turoma variabilis^ Mich. Ic. xxxv. 1-8. Senonian, 

 Touraine, 



T. variabilis and sulcata, Court. 



2. Turonia constricta^ Zitt., sp. n. Irregularly pyriform, 

 with broad, almost horizontally truncate base, furnished 

 with numerous blunt tubercles and depressions. Upper part 

 elongated, bluntly conical, with irregular transverse constric- 

 tions ; in the vertex usually a shallow depression from 

 which furrows originate, which run down the sides, and divide 

 below into fine branches. The smooth covering layer gene- 

 rally coats only the base. Abundant in the Muci'onatus-chslk. 

 of Ahlten. 



3. Turonia induta^ Zitt., sp. n. Small, nodular or lobate, 

 almost entirely coated with epidermis. ^wac^ra^ws-chalk, 

 Linden. 



? 4. Hippalimus depressus^ Rom. Spongit. x. 2. Senonian. 



Theonella, Gray, 



(Proc. Zool. Soc. 1868, p. 565.) 



{Recetit.) Cup-shaped, thick- walled ; central cavity simple, 

 base broad. Skeleton of small quadriradiates with strongly 

 branched ends. Surface anchors with a short shaft and three 

 forked, curved, horizontal prongs. 



1. Theonella Sivinhoei, Gray. Formosa. 



2. Dactylocalyx Pratti, Bow. P. Z. S. 1869, p. 89, pi. v. 

 figs. 6-11. 



3. Theonella f err uginea^ Hack. The skeletal corpuscles of 

 this species have smooth branches. 



