202 BRITISH JURASSIC SPONGES. 
The ostia are not shown. The spicular structure is closely similar to that of the 
preceding species, from which it mainly differs in the larger size of the tubes. 
So far as can be judged from the surface, the arrangement and character of the 
tubes in this form are very similar to those of Verrucocelia (Mastospongia) 
gregaria, Quenstedt (‘ Petref. Deutschl.,’ vol. v, p. 148, pl. cxxu, figs. 8—10) 
with which it also agrees in spicular structure. 
Distribution.—Inferior Oolite. Parkinsoni-zone in the Cliff-section at Burton 
Bradstock, Dorset. (Coll. Rev. G. F. Whidborne.) 
Genus.—StTavuRODERMA, Zittel. 
1877. Studien tiber fossile Spongien, I. Abhandl. der k. bayer. Akademie der 
Wiss., Cl. ii, Bd. xii, Abth. i, p. 53. 
Syn.—Scyphia, Auct; Cribrospongia, d’Orbigny (in part). 
Infundibuliform or platter-shaped sponges with thick walls. The upper or 
inner surface with numerous apertures of cloacal tubes, whilst the under or outer 
surface of the wall is reticulate as in Tremadictyon. The’ canals pass obliquely 
through the wall, and after extending a distance beneath the inner surface open 
into the cloacal tubes. Skeleton mesh irregular, the nodes thickened or 
irregularly widened. Both surfaces of the wall furnished with a dermal layer 
consisting of moderately-sized, cruciform spicules cemented together. The type 
species is Stawroderma (Spongites) Lochense, Quenstedt (‘Der Jura,’ p. 669, 
pl. Ixxxi, fig. 96), from the Upper Jura of Streitberg, Germany. 
9, STAURODERMA EXPLANATUM, Hinde, sp. nov. Plate X, figs. 5, 5a. 
The entire form of sponge unknown; the specimens consist of flattened 
plate-like fragments, some of which are 120 mm. in length by 80 mm. in width, 
whilst the walls reach to 16 mm. in thickness. The upper surface is smooth, 
with nearly circular oscular apertures about 4 mm. in diameter, regularly arranged 
in quincunx, about 10 mm. apart. The under surface is concealed by matrix. 
The spicular mesh of the interior, as seen in thin sections of the wall, is very 
irregular; the nodes are widened by unequal deposition of silica, so that the 
Hexactinellid character is completely masked. Here and there on the smooth 
upper surface, traces of the dermal layer can be distinguished. It consists of 
