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



three very short prongs, which are generally forked. Smooth 

 hacillar spicules also occur. 



The skeletal coi-puscles from the Greensand of Haldon, 

 figured by Carter (Ann. & Mag. Nat. Hist. 1871, vol. vii. 

 pi. viii.) , very probably belong to this genus, as also the anchors 

 figured by him [h c. pi. x.) under the name of Oeodites haldo- 

 nensis. An example of the spicules described by Carter as 

 Monilites {I. c. pi. ix. figs. 46, 47) has also occurred in Dory- 

 derma. 



1. Polyjerea dichotoma^ Rom. Spong. xvi. 1 ; Quenst. Petr. 

 cxxxv. 10, 11. "Senonian. 



2. ? Spong ia ramosa, Msijxt. Geol. Sussex, xv. 11. Seno- 

 nian. 



3. Doryderma cylindrica, ZItt. 



Simple, cylindrical, narrowed above, below with a short 

 stalk. Several scattered vertical tubes in the interior. In 

 the Mucronatus-Q\\a\k of Ahlten and Biewende. 



Lyidium, O. Schmidt. 



(Atlant. Spoug.) 



{Recent.) Sponge basin-shaped, on both surfaces with the 

 large, round ostia of simple canals. Skeletal corpuscles 

 smooth, crooked, branched, the branches terminating in a 

 disciform or cup-shaped dilatation. In the sarcode of the 

 surface numerous simple bacillar spicules of considerable 

 size. (Species Lyidium torquilla, Schm. Cuba. See p. 244.) 



Caeterella, Zitt. 



Jerea p, p., Rom., Giimb. 

 JEnlespoiu/m p. p., Quenst. 



Sponge cylindrical, much elongate, narrowed below ; vertex 

 rounded off, convex, with the scattered apertures of several 

 round, quill-like vertical tubes, which traverse the whole 

 sponge. Surface with irregular, usually elongate, ostia ; 

 below with longitudinal furrows. Numerous fine horizontal 

 radial canals run from the surface to the centre. Corpuscles 

 large, filiform, undulated or crooked, blunt, with long and 

 large axial canals, sometimes with short tubercles, and some- 

 times slightly branched at the ends. They are grouped into 

 thick cords parallel to the main axis, and closely interwoven. 

 Among them in parts are small, strongly branched and tuber- 

 cular corpuscles. Cretaceous. 



